644966436 has 24 divisors (see below), whose sum is σ = 1505645344. Its totient is φ = 214885440.

The previous prime is 644966423. The next prime is 644966459. The reversal of 644966436 is 634669446.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 15591 + ... + 39153.

Almost surely, 2^644966436 is an apocalyptic number.

It is an amenable number.

644966436 is an abundant number, since it is smaller than the sum of its proper divisors (860678908).

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

644966436 is a wasteful number, since it uses less digits than its factorization.

644966436 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25851 (or 25849 counting only the distinct ones).

The product of its digits is 2239488, while the sum is 48.

The square root of 644966436 is about 25396.1893991992. The cubic root of 644966436 is about 863.9972725823.

The spelling of 644966436 in words is "six hundred forty-four million, nine hundred sixty-six thousand, four hundred thirty-six".