644090755 has 16 divisors (see below), whose sum is σ = 963627264. Its totient is φ = 401510880.

The previous prime is 644090743. The next prime is 644090761. The reversal of 644090755 is 557090446.

It is not a de Polignac number, because 644090755 - 2⁵ = 644090723 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 836097 + ... + 836866.

It is an arithmetic number, because the mean of its divisors is an integer number (60226704).

Almost surely, 2^644090755 is an apocalyptic number.

644090755 is a deficient number, since it is larger than the sum of its proper divisors (319536509).

644090755 is a wasteful number, since it uses less digits than its factorization.

644090755 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1672986.

The product of its (nonzero) digits is 151200, while the sum is 40.

The square root of 644090755 is about 25378.9431419041. The cubic root of 644090755 is about 863.6060746214.

The spelling of 644090755 in words is "six hundred forty-four million, ninety thousand, seven hundred fifty-five".