645978333764 has 48 divisors (see below), whose sum is σ = 1163951002368. Its totient is φ = 313519469088.

The previous prime is 645978333751. The next prime is 645978333769. The reversal of 645978333764 is 467333879546.

It is a Smith number, since the sum of its digits (65) coincides with the sum of the digits of its prime factors.

It is a self number, because there is not a number n which added to its sum of digits gives 645978333764.

It is not an unprimeable number, because it can be changed into a prime (645978333769) 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, 21967079 + ... + 21996465.

It is an arithmetic number, because the mean of its divisors is an integer number (24248979216).

Almost surely, 2^645978333764 is an apocalyptic number.

It is an amenable number.

645978333764 is a deficient number, since it is larger than the sum of its proper divisors (517972668604).

645978333764 is a wasteful number, since it uses less digits than its factorization.

645978333764 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30224 (or 30222 counting only the distinct ones).

The product of its digits is 274337280, while the sum is 65.

The spelling of 645978333764 in words is "six hundred forty-five billion, nine hundred seventy-eight million, three hundred thirty-three thousand, seven hundred sixty-four".