631571021 has 2 divisors, whose sum is σ = 631571022. Its totient is φ = 631571020.

The previous prime is 631570999. The next prime is 631571027. The reversal of 631571021 is 120175136.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 609349225 + 22221796 = 24685^2 + 4714^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-631571021 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (631571027) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 315785510 + 315785511.

It is an arithmetic number, because the mean of its divisors is an integer number (315785511).

Almost surely, 2^631571021 is an apocalyptic number.

It is an amenable number.

631571021 is a deficient number, since it is larger than the sum of its proper divisors (1).

631571021 is an equidigital number, since it uses as much as digits as its factorization.

631571021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1260, while the sum is 26.

The square root of 631571021 is about 25131.0767974633. The cubic root of 631571021 is about 857.9738768551.

The spelling of 631571021 in words is "six hundred thirty-one million, five hundred seventy-one thousand, twenty-one".