645981894208 has 56 divisors (see below), whose sum is σ = 1465247361600. Its totient is φ = 276801627648.

The previous prime is 645981894193. The next prime is 645981894209. The reversal of 645981894208 is 802498189546.

It is a tau number, because it is divible by the number of its divisors (56).

It is a Harshad number since it is a multiple of its sum of digits (64).

It is a self number, because there is not a number n which added to its sum of digits gives 645981894208.

It is not an unprimeable number, because it can be changed into a prime (645981894209) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2539278 + ... + 2782066.

Almost surely, 2^645981894208 is an apocalyptic number.

It is an amenable number.

645981894208 is an abundant number, since it is smaller than the sum of its proper divisors (819265467392).

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

645981894208 is a wasteful number, since it uses less digits than its factorization.

645981894208 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 248747 (or 248737 counting only the distinct ones).

The product of its (nonzero) digits is 39813120, while the sum is 64.

The spelling of 645981894208 in words is "six hundred forty-five billion, nine hundred eighty-one million, eight hundred ninety-four thousand, two hundred eight".