640633641 has 16 divisors (see below), whose sum is σ = 873295104. Its totient is φ = 417550464.

The previous prime is 640633613. The next prime is 640633667. The reversal of 640633641 is 146336046.

640633641 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 640633641 - 2⁹ = 640633129 is a prime.

It is a super-2 number, since 2×640633641² = 820822923961833762, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (640633601) 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, 172581 + ... + 176253.

It is an arithmetic number, because the mean of its divisors is an integer number (54580944).

Almost surely, 2^640633641 is an apocalyptic number.

It is an amenable number.

640633641 is a deficient number, since it is larger than the sum of its proper divisors (232661463).

640633641 is a wasteful number, since it uses less digits than its factorization.

640633641 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4960.

The product of its (nonzero) digits is 31104, while the sum is 33.

The square root of 640633641 is about 25310.7416129990. The cubic root of 640633641 is about 862.0581859866.

Adding to 640633641 its reverse (146336046), we get a palindrome (786969687).

The spelling of 640633641 in words is "six hundred forty million, six hundred thirty-three thousand, six hundred forty-one".