644288 has 14 divisors (see below), whose sum is σ = 1278636. Its totient is φ = 322112.

The previous prime is 644261. The next prime is 644291. The reversal of 644288 is 882446.

It is a Harshad number since it is a multiple of its sum of digits (32).

It is an Ulam number.

It is an unprimeable number.

644288 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4970 + ... + 5097.

2⁶⁴⁴²⁸⁸ is an apocalyptic number.

It is an amenable number.

644288 is a deficient number, since it is larger than the sum of its proper divisors (634348).

644288 is a wasteful number, since it uses less digits than its factorization.

644288 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10079 (or 10069 counting only the distinct ones).

The product of its digits is 12288, while the sum is 32.

The square root of 644288 is about 802.6755259755. The cubic root of 644288 is about 86.3694221928.

The spelling of 644288 in words is "six hundred forty-four thousand, two hundred eighty-eight".