644877722 has 4 divisors (see below), whose sum is σ = 967316586. Its totient is φ = 322438860.

The previous prime is 644877671. The next prime is 644877733. The reversal of 644877722 is 227778446.

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

It can be written as a sum of positive squares in only one way, i.e., 612513001 + 32364721 = 24749^2 + 5689^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 161219429 + ... + 161219432.

Almost surely, 2^644877722 is an apocalyptic number.

644877722 is a deficient number, since it is larger than the sum of its proper divisors (322438864).

644877722 is a wasteful number, since it uses less digits than its factorization.

644877722 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 322438863.

The product of its digits is 1053696, while the sum is 47.

The square root of 644877722 is about 25394.4427385206. The cubic root of 644877722 is about 863.9576569970.

The spelling of 644877722 in words is "six hundred forty-four million, eight hundred seventy-seven thousand, seven hundred twenty-two".