664731631 has 2 divisors, whose sum is σ = 664731632. Its totient is φ = 664731630.

The previous prime is 664731629. The next prime is 664731659. The reversal of 664731631 is 136137466.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 664731631 - 2¹ = 664731629 is a prime.

It is a super-2 number, since 2×664731631² = 883736282503840322, which contains 22 as substring.

Together with 664731629, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (664731931) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 332365815 + 332365816.

It is an arithmetic number, because the mean of its divisors is an integer number (332365816).

Almost surely, 2^664731631 is an apocalyptic number.

664731631 is a deficient number, since it is larger than the sum of its proper divisors (1).

664731631 is an equidigital number, since it uses as much as digits as its factorization.

664731631 is an evil number, because the sum of its binary digits is even.

The product of its digits is 54432, while the sum is 37.

The square root of 664731631 is about 25782.3899396468. The cubic root of 664731631 is about 872.7344409860.

The spelling of 664731631 in words is "six hundred sixty-four million, seven hundred thirty-one thousand, six hundred thirty-one".