31967921 has 2 divisors, whose sum is σ = 31967922. Its totient is φ = 31967920.

The previous prime is 31967917. The next prime is 31967933. The reversal of 31967921 is 12976913.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 23902321 + 8065600 = 4889^2 + 2840^2 .

It is a cyclic number.

It is not a de Polignac number, because 31967921 - 2² = 31967917 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is equal to p_1971947 and since 31967921 and 1971947 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 (31967951) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15983960 + 15983961.

It is an arithmetic number, because the mean of its divisors is an integer number (15983961).

Almost surely, 2^31967921 is an apocalyptic number.

It is an amenable number.

31967921 is a deficient number, since it is larger than the sum of its proper divisors (1).

31967921 is an equidigital number, since it uses as much as digits as its factorization.

31967921 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 20412, while the sum is 38.

The square root of 31967921 is about 5654.0181287293. The cubic root of 31967921 is about 317.3740869274.

The spelling of 31967921 in words is "thirty-one million, nine hundred sixty-seven thousand, nine hundred twenty-one".