215621306640 has 120 divisors (see below), whose sum is σ = 750947852928. Its totient is φ = 57499009920.

The previous prime is 215621306629. The next prime is 215621306657. The reversal of 215621306640 is 46603126512.

215621306640 is a `hidden beast` number, since 2 + 1 + 5 + 6 + 2 + 1 + 3 + 0 + 6 + 640 = 666.

It is a tau number, because it is divible by the number of its divisors (120).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 215621306595 and 215621306604.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 5526376 + ... + 5565255.

Almost surely, 2^215621306640 is an apocalyptic number.

215621306640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

215621306640 is an abundant number, since it is smaller than the sum of its proper divisors (535326546288).

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

215621306640 is a wasteful number, since it uses less digits than its factorization.

215621306640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11091659 (or 11091641 counting only the distinct ones).

The product of its (nonzero) digits is 51840, while the sum is 36.

The spelling of 215621306640 in words is "two hundred fifteen billion, six hundred twenty-one million, three hundred six thousand, six hundred forty".