644920432 has 40 divisors (see below), whose sum is σ = 1424815056. Its totient is φ = 280144896.

The previous prime is 644920427. The next prime is 644920453. The reversal of 644920432 is 234029446.

It is a super-2 number, since 2×644920432² = 831844727222133248, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (34).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 87658 + ... + 94729.

Almost surely, 2^644920432 is an apocalyptic number.

It is an amenable number.

644920432 is an abundant number, since it is smaller than the sum of its proper divisors (779894624).

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

644920432 is a wasteful number, since it uses less digits than its factorization.

644920432 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 182425 (or 182419 counting only the distinct ones).

The product of its (nonzero) digits is 41472, while the sum is 34.

The square root of 644920432 is about 25395.2836566162. The cubic root of 644920432 is about 863.9767297688.

Adding to 644920432 its reverse (234029446), we get a palindrome (878949878).

The spelling of 644920432 in words is "six hundred forty-four million, nine hundred twenty thousand, four hundred thirty-two".