644730644 has 12 divisors (see below), whose sum is σ = 1194648084. Its totient is φ = 303402624.

The previous prime is 644730643. The next prime is 644730659. The reversal of 644730644 is 446037446.

It can be written as a sum of positive squares in 2 ways, for example, as 355322500 + 289408144 = 18850^2 + 17012^2 .

It is a junction number, because it is equal to n+sod(n) for n = 644730598 and 644730607.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644730643) 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, 4740599 + ... + 4740734.

It is an arithmetic number, because the mean of its divisors is an integer number (99554007).

Almost surely, 2^644730644 is an apocalyptic number.

It is an amenable number.

644730644 is a deficient number, since it is larger than the sum of its proper divisors (549917440).

644730644 is a wasteful number, since it uses less digits than its factorization.

644730644 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9481354 (or 9481352 counting only the distinct ones).

The product of its (nonzero) digits is 193536, while the sum is 38.

The square root of 644730644 is about 25391.5467035783. The cubic root of 644730644 is about 863.8919707325.

The spelling of 644730644 in words is "six hundred forty-four million, seven hundred thirty thousand, six hundred forty-four".