644377990 has 16 divisors (see below), whose sum is σ = 1184559552. Its totient is φ = 252266944.

The previous prime is 644377973. The next prime is 644378011. The reversal of 644377990 is 99773446.

It is a congruent number.

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, 685039 + ... + 685978.

It is an arithmetic number, because the mean of its divisors is an integer number (74034972).

Almost surely, 2^644377990 is an apocalyptic number.

644377990 is a deficient number, since it is larger than the sum of its proper divisors (540181562).

644377990 is a wasteful number, since it uses less digits than its factorization.

644377990 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1371071.

The product of its (nonzero) digits is 1143072, while the sum is 49.

The square root of 644377990 is about 25384.6014347281. The cubic root of 644377990 is about 863.7344318050.

It can be divided in two parts, 64437 and 7990, that added together give a palindrome (72427).

The spelling of 644377990 in words is "six hundred forty-four million, three hundred seventy-seven thousand, nine hundred ninety".