640344720 has 40 divisors (see below), whose sum is σ = 1985069376. Its totient is φ = 170758528.

The previous prime is 640344701. The next prime is 640344743. The reversal of 640344720 is 27443046.

640344720 is digitally balanced in base 6, because in such base it contains all the possibile digits an equal number of times.

It is a tau number, because it is divible by the number of its divisors (40).

It is a Harshad number since it is a multiple of its sum of digits (30).

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1333812 + ... + 1334291.

Almost surely, 2^640344720 is an apocalyptic number.

640344720 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

640344720 is an abundant number, since it is smaller than the sum of its proper divisors (1344724656).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

640344720 is a wasteful number, since it uses less digits than its factorization.

640344720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2668119 (or 2668113 counting only the distinct ones).

The product of its (nonzero) digits is 16128, while the sum is 30.

The square root of 640344720 is about 25305.0334913827. The cubic root of 640344720 is about 861.9285725596.

Adding to 640344720 its reverse (27443046), we get a palindrome (667787766).

The spelling of 640344720 in words is "six hundred forty million, three hundred forty-four thousand, seven hundred twenty".