31261921 has 2 divisors, whose sum is σ = 31261922. Its totient is φ = 31261920.

The previous prime is 31261907. The next prime is 31261949. The reversal of 31261921 is 12916213.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 31192225 + 69696 = 5585^2 + 264^2 .

It is a cyclic number.

It is not a de Polignac number, because 31261921 - 2⁵ = 31261889 is a prime.

It is a super-2 number, since 2×31261921² = 1954615409220482, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (31261121) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15630960 + 15630961.

It is an arithmetic number, because the mean of its divisors is an integer number (15630961).

Almost surely, 2^31261921 is an apocalyptic number.

It is an amenable number.

31261921 is a deficient number, since it is larger than the sum of its proper divisors (1).

31261921 is an equidigital number, since it uses as much as digits as its factorization.

31261921 is an evil number, because the sum of its binary digits is even.

The product of its digits is 648, while the sum is 25.

The square root of 31261921 is about 5591.2360887374. The cubic root of 31261921 is about 315.0203094321.

The spelling of 31261921 in words is "thirty-one million, two hundred sixty-one thousand, nine hundred twenty-one".