31724321 has 2 divisors, whose sum is σ = 31724322. Its totient is φ = 31724320.

The previous prime is 31724311. The next prime is 31724327. The reversal of 31724321 is 12342713.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 25150225 + 6574096 = 5015^2 + 2564^2 .

It is a cyclic number.

It is not a de Polignac number, because 31724321 - 2⁶ = 31724257 is a prime.

It is a super-2 number, since 2×31724321² = 2012865085822082, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (31724327) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15862160 + 15862161.

It is an arithmetic number, because the mean of its divisors is an integer number (15862161).

Almost surely, 2^31724321 is an apocalyptic number.

It is an amenable number.

31724321 is a deficient number, since it is larger than the sum of its proper divisors (1).

31724321 is an equidigital number, since it uses as much as digits as its factorization.

31724321 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1008, while the sum is 23.

The square root of 31724321 is about 5632.4347310910. The cubic root of 31724321 is about 316.5658856886.

The spelling of 31724321 in words is "thirty-one million, seven hundred twenty-four thousand, three hundred twenty-one".