644831 has 12 divisors (see below), whose sum is σ = 738792. Its totient is φ = 558000.

The previous prime is 644801. The next prime is 644837. The reversal of 644831 is 138446.

It is not a de Polignac number, because 644831 - 2⁶ = 644767 is a prime.

It is a super-2 number, since 2×644831² = 831614037122, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 644831.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644837) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 10541 + ... + 10601.

It is an arithmetic number, because the mean of its divisors is an integer number (61566).

2⁶⁴⁴⁸³¹ is an apocalyptic number.

644831 is a gapful number since it is divisible by the number (61) formed by its first and last digit.

644831 is a deficient number, since it is larger than the sum of its proper divisors (93961).

644831 is a wasteful number, since it uses less digits than its factorization.

644831 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 134 (or 103 counting only the distinct ones).

The product of its digits is 2304, while the sum is 26.

The square root of 644831 is about 803.0136985133. The cubic root of 644831 is about 86.3936791644.

The spelling of 644831 in words is "six hundred forty-four thousand, eight hundred thirty-one".