644825 has 6 divisors (see below), whose sum is σ = 799614. Its totient is φ = 515840.

The previous prime is 644801. The next prime is 644837. The reversal of 644825 is 528446.

644825 is nontrivially palindromic in base 16.

It can be written as a sum of positive squares in 3 ways, for example, as 16 + 644809 = 4^2 + 803^2 .

It is not a de Polignac number, because 644825 - 2⁸ = 644569 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 12872 + ... + 12921.

It is an arithmetic number, because the mean of its divisors is an integer number (133269).

2⁶⁴⁴⁸²⁵ is an apocalyptic number.

It is an amenable number.

644825 is a deficient number, since it is larger than the sum of its proper divisors (154789).

644825 is a wasteful number, since it uses less digits than its factorization.

644825 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25803 (or 25798 counting only the distinct ones).

The product of its digits is 7680, while the sum is 29.

The square root of 644825 is about 803.0099625783. The cubic root of 644825 is about 86.3934112059.

The spelling of 644825 in words is "six hundred forty-four thousand, eight hundred twenty-five".