645621103656 has 64 divisors (see below), whose sum is σ = 1813542480000. Its totient is φ = 212788971648.

The previous prime is 645621103591. The next prime is 645621103693. The reversal of 645621103656 is 656301126546.

645621103656 is a `hidden beast` number, since 6 + 4 + 5 + 621 + 10 + 3 + 6 + 5 + 6 = 666.

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, 16772836 + ... + 16811283.

It is an arithmetic number, because the mean of its divisors is an integer number (28336601250).

Almost surely, 2^645621103656 is an apocalyptic number.

It is an amenable number.

645621103656 is an abundant number, since it is smaller than the sum of its proper divisors (1167921376344).

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

645621103656 is a wasteful number, since it uses less digits than its factorization.

645621103656 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33584223 (or 33584213 counting only the distinct ones).

The product of its (nonzero) digits is 777600, while the sum is 45.

The spelling of 645621103656 in words is "six hundred forty-five billion, six hundred twenty-one million, one hundred three thousand, six hundred fifty-six".