644964755 has 16 divisors (see below), whose sum is σ = 786477600. Its totient is φ = 507682560.

The previous prime is 644964739. The next prime is 644964763. The reversal of 644964755 is 557469446.

It is not a de Polignac number, because 644964755 - 2⁴ = 644964739 is a prime.

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, 90461 + ... + 97329.

It is an arithmetic number, because the mean of its divisors is an integer number (49154850).

Almost surely, 2^644964755 is an apocalyptic number.

644964755 is a deficient number, since it is larger than the sum of its proper divisors (141512845).

644964755 is a wasteful number, since it uses less digits than its factorization.

644964755 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7174.

The product of its digits is 3628800, while the sum is 50.

The square root of 644964755 is about 25396.1563036614. The cubic root of 644964755 is about 863.9965219589.

The spelling of 644964755 in words is "six hundred forty-four million, nine hundred sixty-four thousand, seven hundred fifty-five".