646708631 has 4 divisors (see below), whose sum is σ = 646787232. Its totient is φ = 646630032.

The previous prime is 646708627. The next prime is 646708651. The reversal of 646708631 is 136807646.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 646708631 - 2² = 646708627 is a prime.

It is a super-2 number, since 2×646708631² = 836464106819788322, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (646708651) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 25295 + ... + 43968.

It is an arithmetic number, because the mean of its divisors is an integer number (161696808).

Almost surely, 2^646708631 is an apocalyptic number.

646708631 is a deficient number, since it is larger than the sum of its proper divisors (78601).

646708631 is an equidigital number, since it uses as much as digits as its factorization.

646708631 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 78600.

The product of its (nonzero) digits is 145152, while the sum is 41.

The square root of 646708631 is about 25430.4665902928. The cubic root of 646708631 is about 864.7745215144.

The spelling of 646708631 in words is "six hundred forty-six million, seven hundred eight thousand, six hundred thirty-one".