31540921 has 2 divisors, whose sum is σ = 31540922. Its totient is φ = 31540920.

The previous prime is 31540871. The next prime is 31540939. The reversal of 31540921 is 12904513.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 31483321 + 57600 = 5611^2 + 240^2 .

It is a cyclic number.

It is not a de Polignac number, because 31540921 - 2¹⁵ = 31508153 is a prime.

It is not a weakly prime, because it can be changed into another prime (31540961) 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, 15770460 + 15770461.

It is an arithmetic number, because the mean of its divisors is an integer number (15770461).

Almost surely, 2^31540921 is an apocalyptic number.

It is an amenable number.

31540921 is a deficient number, since it is larger than the sum of its proper divisors (1).

31540921 is an equidigital number, since it uses as much as digits as its factorization.

31540921 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1080, while the sum is 25.

The square root of 31540921 is about 5616.1304293971. The cubic root of 31540921 is about 315.9546782462.

The spelling of 31540921 in words is "thirty-one million, five hundred forty thousand, nine hundred twenty-one".