664738631 has 2 divisors, whose sum is σ = 664738632. Its totient is φ = 664738630.

The previous prime is 664738537. The next prime is 664738649. The reversal of 664738631 is 136837466.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 664738631 - 2¹⁸ = 664476487 is a prime.

It is a super-2 number, since 2×664738631² = 883754895087508322, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (664738651) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 332369315 + 332369316.

It is an arithmetic number, because the mean of its divisors is an integer number (332369316).

Almost surely, 2^664738631 is an apocalyptic number.

664738631 is a deficient number, since it is larger than the sum of its proper divisors (1).

664738631 is an equidigital number, since it uses as much as digits as its factorization.

664738631 is an evil number, because the sum of its binary digits is even.

The product of its digits is 435456, while the sum is 44.

The square root of 664738631 is about 25782.5256908628. The cubic root of 664738631 is about 872.7375044377.

The spelling of 664738631 in words is "six hundred sixty-four million, seven hundred thirty-eight thousand, six hundred thirty-one".