645251642556 has 48 divisors (see below), whose sum is σ = 1507025520000. Its totient is φ = 214878517312.

The previous prime is 645251642537. The next prime is 645251642599. The reversal of 645251642556 is 655246152546.

It is a junction number, because it is equal to n+sod(n) for n = 645251642499 and 645251642508.

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, 66181570 + ... + 66191318.

It is an arithmetic number, because the mean of its divisors is an integer number (31396365000).

Almost surely, 2^645251642556 is an apocalyptic number.

It is an amenable number.

645251642556 is an abundant number, since it is smaller than the sum of its proper divisors (861773877444).

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

645251642556 is a wasteful number, since it uses less digits than its factorization.

645251642556 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14458 (or 14456 counting only the distinct ones).

The product of its digits is 8640000, while the sum is 51.

The spelling of 645251642556 in words is "six hundred forty-five billion, two hundred fifty-one million, six hundred forty-two thousand, five hundred fifty-six".