644777793 has 32 divisors (see below), whose sum is σ = 1078012800. Its totient is φ = 377294400.

The previous prime is 644777789. The next prime is 644777801. The reversal of 644777793 is 397777446.

It is not a de Polignac number, because 644777793 - 2² = 644777789 is a prime.

It is not an unprimeable number, because it can be changed into a prime (644777723) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 28818 + ... + 46043.

It is an arithmetic number, because the mean of its divisors is an integer number (33687900).

Almost surely, 2^644777793 is an apocalyptic number.

It is an amenable number.

644777793 is a deficient number, since it is larger than the sum of its proper divisors (433235007).

644777793 is a wasteful number, since it uses less digits than its factorization.

644777793 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 74910 (or 74904 counting only the distinct ones).

The product of its digits is 6223392, while the sum is 54.

The square root of 644777793 is about 25392.4751255170. The cubic root of 644777793 is about 863.9130289579.

The spelling of 644777793 in words is "six hundred forty-four million, seven hundred seventy-seven thousand, seven hundred ninety-three".