644425777 has 4 divisors (see below), whose sum is σ = 654990196. Its totient is φ = 633861360.

The previous prime is 644425757. The next prime is 644425801. The reversal of 644425777 is 777524446.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 32160241 + 612265536 = 5671^2 + 24744^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-644425777 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (644425757) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5282118 + ... + 5282239.

It is an arithmetic number, because the mean of its divisors is an integer number (163747549).

Almost surely, 2^644425777 is an apocalyptic number.

It is an amenable number.

644425777 is a deficient number, since it is larger than the sum of its proper divisors (10564419).

644425777 is a wasteful number, since it uses less digits than its factorization.

644425777 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10564418.

The product of its digits is 1317120, while the sum is 46.

The square root of 644425777 is about 25385.5426768860. The cubic root of 644425777 is about 863.7557827603.

The spelling of 644425777 in words is "six hundred forty-four million, four hundred twenty-five thousand, seven hundred seventy-seven".