31564921 has 2 divisors, whose sum is σ = 31564922. Its totient is φ = 31564920.

The previous prime is 31564919. The next prime is 31564927. The reversal of 31564921 is 12946513.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 29822521 + 1742400 = 5461^2 + 1320^2 .

It is a cyclic number.

It is not a de Polignac number, because 31564921 - 2¹ = 31564919 is a prime.

Together with 31564919, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (31564927) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15782460 + 15782461.

It is an arithmetic number, because the mean of its divisors is an integer number (15782461).

Almost surely, 2^31564921 is an apocalyptic number.

It is an amenable number.

31564921 is a deficient number, since it is larger than the sum of its proper divisors (1).

31564921 is an equidigital number, since it uses as much as digits as its factorization.

31564921 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 6480, while the sum is 31.

The square root of 31564921 is about 5618.2667256014. The cubic root of 31564921 is about 316.0347962804.

The spelling of 31564921 in words is "thirty-one million, five hundred sixty-four thousand, nine hundred twenty-one".