644460765 has 32 divisors (see below), whose sum is σ = 1148757120. Its totient is φ = 306329856.

The previous prime is 644460763. The next prime is 644460779. The reversal of 644460765 is 567064446.

It is a happy number.

It is not a de Polignac number, because 644460765 - 2¹ = 644460763 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644460763) 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, 51327 + ... + 62636.

It is an arithmetic number, because the mean of its divisors is an integer number (35898660).

Almost surely, 2^644460765 is an apocalyptic number.

644460765 is a gapful number since it is divisible by the number (65) formed by its first and last digit.

It is an amenable number.

644460765 is a deficient number, since it is larger than the sum of its proper divisors (504296355).

644460765 is a wasteful number, since it uses less digits than its factorization.

644460765 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 114013.

The product of its (nonzero) digits is 483840, while the sum is 42.

The square root of 644460765 is about 25386.2317999344. The cubic root of 644460765 is about 863.7714145271.

The spelling of 644460765 in words is "six hundred forty-four million, four hundred sixty thousand, seven hundred sixty-five".