21956684256 has 240 divisors, whose sum is σ = 69714225504. Its totient is φ = 6739117056.

The previous prime is 21956684251. The next prime is 21956684261. The reversal of 21956684256 is 65248665912.

21956684256 is a `hidden beast` number, since 21 + 9 + 566 + 8 + 4 + 2 + 56 = 666.

It is an interprime number because it is at equal distance from previous prime (21956684251) and next prime (21956684261).

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21956684251) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 25035690 + ... + 25036566.

Almost surely, 2^21956684256 is an apocalyptic number.

21956684256 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21956684256, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34857112752).

21956684256 is an abundant number, since it is smaller than the sum of its proper divisors (47757541248).

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

21956684256 is a wasteful number, since it uses less digits than its factorization.

21956684256 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1655 (or 1638 counting only the distinct ones).

The product of its digits is 6220800, while the sum is 54.

The spelling of 21956684256 in words is "twenty-one billion, nine hundred fifty-six million, six hundred eighty-four thousand, two hundred fifty-six".