644686446 has 32 divisors (see below), whose sum is σ = 1330593408. Its totient is φ = 208081440.

The previous prime is 644686439. The next prime is 644686499.

644686446 is nontrivially palindromic in base 10.

644686446 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a super-2 number, since 2×644686446² = 831241227312221832, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 644686395 and 644686404.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 39961 + ... + 53723.

It is an arithmetic number, because the mean of its divisors is an integer number (41581044).

Almost surely, 2^644686446 is an apocalyptic number.

644686446 is an abundant number, since it is smaller than the sum of its proper divisors (685906962).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

644686446 is a wasteful number, since it uses less digits than its factorization.

644686446 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14016.

The product of its digits is 2654208, while the sum is 48.

The square root of 644686446 is about 25390.6763596404. The cubic root of 644686446 is about 863.8722295842.

The spelling of 644686446 in words is "six hundred forty-four million, six hundred eighty-six thousand, four hundred forty-six".