641638664 has 16 divisors (see below), whose sum is σ = 1266392400. Its totient is φ = 303934032.

The previous prime is 641638663. The next prime is 641638681. The reversal of 641638664 is 466836146.

It is not an unprimeable number, because it can be changed into a prime (641638663) 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, 2110502 + ... + 2110805.

It is an arithmetic number, because the mean of its divisors is an integer number (79149525).

Almost surely, 2^641638664 is an apocalyptic number.

It is an amenable number.

641638664 is a deficient number, since it is larger than the sum of its proper divisors (624753736).

641638664 is a wasteful number, since it uses less digits than its factorization.

641638664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4221332 (or 4221328 counting only the distinct ones).

The product of its digits is 497664, while the sum is 44.

The square root of 641638664 is about 25330.5875178607. The cubic root of 641638664 is about 862.5087480454.

It can be divided in two parts, 64163 and 8664, that added together give a palindrome (72827).

The spelling of 641638664 in words is "six hundred forty-one million, six hundred thirty-eight thousand, six hundred sixty-four".