21660536002056 has 384 divisors, whose sum is σ = 66028395144960. Its totient is φ = 5892937881600.

The previous prime is 21660536002051. The next prime is 21660536002067. The reversal of 21660536002056 is 65020063506612.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a junction number, because it is equal to n+sod(n) for n = 21660536001999 and 21660536002017.

It is not an unprimeable number, because it can be changed into a prime (21660536002051) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 9097241986 + ... + 9097244366.

It is an arithmetic number, because the mean of its divisors is an integer number (171948945690).

Almost surely, 2^{21660536002056} is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21660536002056, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33014197572480).

21660536002056 is an abundant number, since it is smaller than the sum of its proper divisors (44367859142904).

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

21660536002056 is a wasteful number, since it uses less digits than its factorization.

21660536002056 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3805 (or 3794 counting only the distinct ones).

The product of its (nonzero) digits is 388800, while the sum is 42.

Adding to 21660536002056 its reverse (65020063506612), we get a palindrome (86680599508668).

The spelling of 21660536002056 in words is "twenty-one trillion, six hundred sixty billion, five hundred thirty-six million, two thousand, fifty-six".