21967331 has 2 divisors, whose sum is σ = 21967332. Its totient is φ = 21967330.

The previous prime is 21967303. The next prime is 21967333. The reversal of 21967331 is 13376912.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21967331 is a prime.

It is a super-2 number, since 2×21967331² = 965127262527122, which contains 22 as substring.

It is a Sophie Germain prime.

Together with 21967333, it forms a pair of twin primes.

It is a Chen prime.

It is equal to p_1387328 and since 21967331 and 1387328 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (21967333) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10983665 + 10983666.

It is an arithmetic number, because the mean of its divisors is an integer number (10983666).

Almost surely, 2^21967331 is an apocalyptic number.

21967331 is a deficient number, since it is larger than the sum of its proper divisors (1).

21967331 is an equidigital number, since it uses as much as digits as its factorization.

21967331 is an evil number, because the sum of its binary digits is even.

The product of its digits is 6804, while the sum is 32.

The square root of 21967331 is about 4686.9319389127. The cubic root of 21967331 is about 280.0651676547.

The spelling of 21967331 in words is "twenty-one million, nine hundred sixty-seven thousand, three hundred thirty-one".