78344390640 has 80 divisors (see below), whose sum is σ = 244224547200. Its totient is φ = 20775111936.

The previous prime is 78344390611. The next prime is 78344390681. The reversal of 78344390640 is 4609344387.

It is a tau number, because it is divible by the number of its divisors (80).

It is a super-2 number, since 2×78344390640² (a number of 23 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (48).

It is a self number, because there is not a number n which added to its sum of digits gives 78344390640.

It is a congruent number.

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, 868870 + ... + 954789.

It is an arithmetic number, because the mean of its divisors is an integer number (3052806840).

Almost surely, 2^78344390640 is an apocalyptic number.

It is an amenable number.

78344390640 is an abundant number, since it is smaller than the sum of its proper divisors (165880156560).

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

78344390640 is a wasteful number, since it uses less digits than its factorization.

78344390640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1823854 (or 1823848 counting only the distinct ones).

The product of its (nonzero) digits is 1741824, while the sum is 48.

The spelling of 78344390640 in words is "seventy-eight billion, three hundred forty-four million, three hundred ninety thousand, six hundred forty".