644655375 has 128 divisors (see below), whose sum is σ = 1467648000. Its totient is φ = 271900800.

The previous prime is 644655373. The next prime is 644655379. The reversal of 644655375 is 573556446.

644655375 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 644655375 - 2¹ = 644655373 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a self number, because there is not a number n which added to its sum of digits gives 644655375.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644655371) by changing a digit.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 306076 + ... + 308174.

It is an arithmetic number, because the mean of its divisors is an integer number (11466000).

Almost surely, 2^644655375 is an apocalyptic number.

644655375 is a gapful number since it is divisible by the number (65) formed by its first and last digit.

644655375 is an abundant number, since it is smaller than the sum of its proper divisors (822992625).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

644655375 is a wasteful number, since it uses less digits than its factorization.

644655375 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2143 (or 2127 counting only the distinct ones).

The product of its digits is 1512000, while the sum is 45.

The square root of 644655375 is about 25390.0644938133. The cubic root of 644655375 is about 863.8583511034.

The spelling of 644655375 in words is "six hundred forty-four million, six hundred fifty-five thousand, three hundred seventy-five".