644402401320 has 64 divisors (see below), whose sum is σ = 1933280435520. Its totient is φ = 171834130944.

The previous prime is 644402401301. The next prime is 644402401393. The reversal of 644402401320 is 23104204446.

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 15 ways as a sum of consecutive naturals, for example, 3655119 + ... + 3827361.

It is an arithmetic number, because the mean of its divisors is an integer number (30207506805).

Almost surely, 2^644402401320 is an apocalyptic number.

644402401320 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

644402401320 is an abundant number, since it is smaller than the sum of its proper divisors (1288878034200).

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

644402401320 is a wasteful number, since it uses less digits than its factorization.

644402401320 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 203434 (or 203430 counting only the distinct ones).

The product of its (nonzero) digits is 18432, while the sum is 30.

Adding to 644402401320 its reverse (23104204446), we get a palindrome (667506605766).

The spelling of 644402401320 in words is "six hundred forty-four billion, four hundred two million, four hundred one thousand, three hundred twenty".