644163632 has 40 divisors (see below), whose sum is σ = 1472381952. Its totient is φ = 267163200.

The previous prime is 644163629. The next prime is 644163649. The reversal of 644163632 is 236361446.

It is a junction number, because it is equal to n+sod(n) for n = 644163592 and 644163601.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 89294 + ... + 96237.

Almost surely, 2^644163632 is an apocalyptic number.

644163632 is a gapful number since it is divisible by the number (62) formed by its first and last digit.

It is an amenable number.

644163632 is an abundant number, since it is smaller than the sum of its proper divisors (828218320).

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

644163632 is a wasteful number, since it uses less digits than its factorization.

644163632 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 185577 (or 185571 counting only the distinct ones).

The product of its digits is 62208, while the sum is 35.

The square root of 644163632 is about 25380.3788781807. The cubic root of 644163632 is about 863.6386449002.

The spelling of 644163632 in words is "six hundred forty-four million, one hundred sixty-three thousand, six hundred thirty-two".