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

Related Calculations

See Also

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.

See Also