644636433 has 16 divisors (see below), whose sum is σ = 1025012736. Its totient is φ = 352347600.

The previous prime is 644636423. The next prime is 644636453. The reversal of 644636433 is 334636446.

644636433 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 644636433 - 2⁴ = 644636417 is a prime.

It is a super-2 number, since 2×644636433² = 831112261501926978, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 644636391 and 644636400.

It is not an unprimeable number, because it can be changed into a prime (644636423) 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, 666843 + ... + 667808.

It is an arithmetic number, because the mean of its divisors is an integer number (64063296).

Almost surely, 2^644636433 is an apocalyptic number.

It is an amenable number.

644636433 is a deficient number, since it is larger than the sum of its proper divisors (380376303).

644636433 is a wasteful number, since it uses less digits than its factorization.

644636433 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1334684.

The product of its digits is 373248, while the sum is 39.

The square root of 644636433 is about 25389.6914711463. The cubic root of 644636433 is about 863.8498900632.

The spelling of 644636433 in words is "six hundred forty-four million, six hundred thirty-six thousand, four hundred thirty-three".