644052621 has 16 divisors (see below), whose sum is σ = 887863808. Its totient is φ = 414849600.

The previous prime is 644052611. The next prime is 644052623. The reversal of 644052621 is 126250446.

It is not a de Polignac number, because 644052621 - 2⁵ = 644052589 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644052623) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 56235 + ... + 66711.

It is an arithmetic number, because the mean of its divisors is an integer number (55491488).

Almost surely, 2^644052621 is an apocalyptic number.

It is an amenable number.

644052621 is a deficient number, since it is larger than the sum of its proper divisors (243811187).

644052621 is a wasteful number, since it uses less digits than its factorization.

644052621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11172.

The product of its (nonzero) digits is 11520, while the sum is 30.

The square root of 644052621 is about 25378.1918386634. The cubic root of 644052621 is about 863.5890307480.

The spelling of 644052621 in words is "six hundred forty-four million, fifty-two thousand, six hundred twenty-one".