644931 has 24 divisors (see below), whose sum is σ = 1104480. Its totient is φ = 354816.

The previous prime is 644923. The next prime is 644933. The reversal of 644931 is 139446.

644931 is digitally balanced in base 7, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 644931 - 2³ = 644923 is a prime.

It is a super-2 number, since 2×644931² = 831871989522, which contains 22 as substring.

644931 is strictly pandigital in base 7.

It is a junction number, because it is equal to n+sod(n) for n = 644895 and 644904.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644933) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1651 + ... + 2003.

It is an arithmetic number, because the mean of its divisors is an integer number (46020).

2⁶⁴⁴⁹³¹ is an apocalyptic number.

644931 is a deficient number, since it is larger than the sum of its proper divisors (459549).

644931 is a wasteful number, since it uses less digits than its factorization.

644931 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 395 (or 392 counting only the distinct ones).

The product of its digits is 2592, while the sum is 27.

The square root of 644931 is about 803.0759615379. The cubic root of 644931 is about 86.3981448933.

The spelling of 644931 in words is "six hundred forty-four thousand, nine hundred thirty-one".