644625 has 32 divisors (see below), whose sum is σ = 1198080. Its totient is φ = 342000.

The previous prime is 644617. The next prime is 644629. The reversal of 644625 is 526446.

It is a happy number.

It is not a de Polignac number, because 644625 - 2³ = 644617 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a nialpdrome in base 15.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644629) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 3280 + ... + 3470.

It is an arithmetic number, because the mean of its divisors is an integer number (37440).

2⁶⁴⁴⁶²⁵ is an apocalyptic number.

It is an amenable number.

644625 is a deficient number, since it is larger than the sum of its proper divisors (553455).

644625 is a wasteful number, since it uses less digits than its factorization.

644625 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 215 (or 199 counting only the distinct ones).

The product of its digits is 5760, while the sum is 27.

The square root of 644625 is about 802.8854214644. The cubic root of 644625 is about 86.3844783074.

The spelling of 644625 in words is "six hundred forty-four thousand, six hundred twenty-five".