31396921 has 2 divisors, whose sum is σ = 31396922. Its totient is φ = 31396920.

The previous prime is 31396913. The next prime is 31396933. The reversal of 31396921 is 12969313.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 31236921 + 160000 = 5589^2 + 400^2 .

It is a cyclic number.

It is not a de Polignac number, because 31396921 - 2³ = 31396913 is a prime.

It is not a weakly prime, because it can be changed into another prime (31396621) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15698460 + 15698461.

It is an arithmetic number, because the mean of its divisors is an integer number (15698461).

Almost surely, 2^31396921 is an apocalyptic number.

It is an amenable number.

31396921 is a deficient number, since it is larger than the sum of its proper divisors (1).

31396921 is an equidigital number, since it uses as much as digits as its factorization.

31396921 is an evil number, because the sum of its binary digits is even.

The product of its digits is 8748, while the sum is 34.

The square root of 31396921 is about 5603.2955481574. The cubic root of 31396921 is about 315.4731145303.

The spelling of 31396921 in words is "thirty-one million, three hundred ninety-six thousand, nine hundred twenty-one".