644933125 has 30 divisors (see below), whose sum is σ = 832675646. Its totient is φ = 498996000.

The previous prime is 644933119. The next prime is 644933143. The reversal of 644933125 is 521339446.

It can be written as a sum of positive squares in 5 ways, for example, as 121484484 + 523448641 = 11022^2 + 22879^2 .

It is not a de Polignac number, because 644933125 - 2¹⁹ = 644408837 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (37).

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 29 ways as a sum of consecutive naturals, for example, 3861792 + ... + 3861958.

Almost surely, 2^644933125 is an apocalyptic number.

It is an amenable number.

644933125 is a deficient number, since it is larger than the sum of its proper divisors (187742521).

644933125 is an frugal number, since it uses more digits than its factorization.

644933125 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 391 (or 209 counting only the distinct ones).

The product of its digits is 77760, while the sum is 37.

The square root of 644933125 is about 25395.5335639951. The cubic root of 644933125 is about 863.9823978503.

Multiplying 644933125 by its sum of digits (37), we get a square (23862525625 = 154475²).

644933125 divided by its sum of digits (37) gives a square (17430625 = 4175²).

The spelling of 644933125 in words is "six hundred forty-four million, nine hundred thirty-three thousand, one hundred twenty-five".