644162140 has 36 divisors (see below), whose sum is σ = 1363359816. Its totient is φ = 255657696.

The previous prime is 644162137. The next prime is 644162179. The reversal of 644162140 is 41261446.

It is a junction number, because it is equal to n+sod(n) for n = 644162099 and 644162108.

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 11 ways as a sum of consecutive naturals, for example, 385587 + ... + 387253.

It is an arithmetic number, because the mean of its divisors is an integer number (37871106).

Almost surely, 2^644162140 is an apocalyptic number.

It is an amenable number.

644162140 is an abundant number, since it is smaller than the sum of its proper divisors (719197676).

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

644162140 is a wasteful number, since it uses less digits than its factorization.

644162140 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1954 (or 1813 counting only the distinct ones).

The product of its (nonzero) digits is 4608, while the sum is 28.

The square root of 644162140 is about 25380.3494853794. The cubic root of 644162140 is about 863.6379781184.

The spelling of 644162140 in words is "six hundred forty-four million, one hundred sixty-two thousand, one hundred forty".