644244028 has 12 divisors (see below), whose sum is σ = 1127968632. Its totient is φ = 321967280.

The previous prime is 644243921. The next prime is 644244047. The reversal of 644244028 is 820442446.

It is a super-2 number, since 2×644244028² = 830100735227329568, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 644243984 and 644244002.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 29050 + ... + 46177.

It is an arithmetic number, because the mean of its divisors is an integer number (93997386).

Almost surely, 2^644244028 is an apocalyptic number.

It is an amenable number.

644244028 is a deficient number, since it is larger than the sum of its proper divisors (483724604).

644244028 is a wasteful number, since it uses less digits than its factorization.

644244028 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 77372 (or 77370 counting only the distinct ones).

The product of its (nonzero) digits is 49152, while the sum is 34.

The square root of 644244028 is about 25381.9626506699. The cubic root of 644244028 is about 863.6745727301.

The spelling of 644244028 in words is "six hundred forty-four million, two hundred forty-four thousand, twenty-eight".