21536247656 has 64 divisors (see below), whose sum is σ = 50712151680. Its totient is φ = 8329466880.

The previous prime is 21536247637. The next prime is 21536247659. The reversal of 21536247656 is 65674263512.

It is a hoax number, since the sum of its digits (47) coincides with the sum of the digits of its distinct prime factors.

It is a self number, because there is not a number n which added to its sum of digits gives 21536247656.

It is not an unprimeable number, because it can be changed into a prime (21536247659) 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, 43205 + ... + 211988.

It is an arithmetic number, because the mean of its divisors is an integer number (792377370).

Almost surely, 2^21536247656 is an apocalyptic number.

It is an amenable number.

21536247656 is an abundant number, since it is smaller than the sum of its proper divisors (29175904024).

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

21536247656 is a wasteful number, since it uses less digits than its factorization.

21536247656 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 255354 (or 255350 counting only the distinct ones).

The product of its digits is 1814400, while the sum is 47.

The spelling of 21536247656 in words is "twenty-one billion, five hundred thirty-six million, two hundred forty-seven thousand, six hundred fifty-six".