644137390 has 16 divisors (see below), whose sum is σ = 1248635808. Its totient is φ = 237835296.

The previous prime is 644137381. The next prime is 644137391. The reversal of 644137390 is 93731446.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644137391) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2477322 + ... + 2477581.

It is an arithmetic number, because the mean of its divisors is an integer number (78039738).

Almost surely, 2^644137390 is an apocalyptic number.

644137390 is a deficient number, since it is larger than the sum of its proper divisors (604498418).

644137390 is a wasteful number, since it uses less digits than its factorization.

644137390 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4954923.

The product of its (nonzero) digits is 54432, while the sum is 37.

The square root of 644137390 is about 25379.8618987574. The cubic root of 644137390 is about 863.6269170762.

The spelling of 644137390 in words is "six hundred forty-four million, one hundred thirty-seven thousand, three hundred ninety".