644626523 has 4 divisors (see below), whose sum is σ = 644746248. Its totient is φ = 644506800.

The previous prime is 644626501. The next prime is 644626561. The reversal of 644626523 is 325626446.

644626523 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 644626523 - 2²⁴ = 627849307 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (644626583) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 51386 + ... + 62687.

It is an arithmetic number, because the mean of its divisors is an integer number (161186562).

Almost surely, 2^644626523 is an apocalyptic number.

644626523 is a deficient number, since it is larger than the sum of its proper divisors (119725).

644626523 is a wasteful number, since it uses less digits than its factorization.

644626523 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 119724.

The product of its digits is 207360, while the sum is 38.

The square root of 644626523 is about 25389.4963124517. The cubic root of 644626523 is about 863.8454633839.

The spelling of 644626523 in words is "six hundred forty-four million, six hundred twenty-six thousand, five hundred twenty-three".