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    Is 821 a prime number?

    Prime Number Checker
    Number

    Is 821 a prime or composite number?

    Answer

    Number 821 is a Prime

    821 has exactly two divisors — 1 and 821 — so it is a prime.

    Primes up to √821

    28² = 784 ≤ 821 < 841 = 29², so it is enough to try primes up to 28

    • ÷2 does not divide
    • ÷3 does not divide
    • ÷5 does not divide
    • ÷7 does not divide
    • ÷11 does not divide
    • ÷13 does not divide
    • ÷17 does not divide
    • ÷19 does not divide
    • ÷23 does not divide

    none of the 9 primes up to 28 divides 821 — 821 is prime

    Nearest primes: 811 and 823

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    Is 821 a prime number? Is 821 a prime number? 821 is a prime number. Check if any number is prime or composite with our free online prime checker.
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    Prime numbers list

    NumberIs Prime
    783No: 3³ × 29
    785No: 5 × 157
    787Yes
    790No: 2 × 5 × 79
    791No: 7 × 113
    795No: 3 × 5 × 53
    797Yes
    801No: 3² × 89
    803No: 11 × 73
    809Yes
    811Yes
    812No: 2² × 7 × 29
    813No: 3 × 271
    817No: 19 × 43
    819No: 3² × 7 × 13
    821Yes
    822No: 2 × 3 × 137
    823Yes
    827Yes
    829Yes
    831No: 3 × 277
    833No: 7² × 17
    835No: 5 × 167
    841No: 29²
    843No: 3 × 281
    847No: 7 × 11²
    853Yes
    857Yes
    863Yes
    865No: 5 × 173

    FAQ

    Is 821 a prime or composite number?

    Number 821 is a Prime

    How many factors are in a number 821?

    2

    How to check if 821 is prime?

    Divide 821 by the primes in order: 28² = 784 ≤ 821 < 841 = 29², so it is enough to try primes up to 28. None of the 9 primes up to 28 divides 821, so 821 is prime.

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