21172461156 has 384 divisors, whose sum is σ = 70447104000. Its totient is φ = 5451183360.

The previous prime is 21172461151. The next prime is 21172461179. The reversal of 21172461156 is 65116427112.

21172461156 is a `hidden beast` number, since 2 + 1 + 17 + 24 + 611 + 5 + 6 = 666.

It is a super-2 number, since 2×21172461156² (a number of 21 digits) contains 22 as substring.

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

It is a self number, because there is not a number n which added to its sum of digits gives 21172461156.

It is not an unprimeable number, because it can be changed into a prime (21172461151) by changing a digit.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 90868816 + ... + 90869048.

It is an arithmetic number, because the mean of its divisors is an integer number (183456000).

Almost surely, 2^21172461156 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 21172461156, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35223552000).

21172461156 is an abundant number, since it is smaller than the sum of its proper divisors (49274642844).

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

21172461156 is a wasteful number, since it uses less digits than its factorization.

21172461156 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 501 (or 479 counting only the distinct ones).

The product of its digits is 20160, while the sum is 36.

Adding to 21172461156 its reverse (65116427112), we get a palindrome (86288888268).

The spelling of 21172461156 in words is "twenty-one billion, one hundred seventy-two million, four hundred sixty-one thousand, one hundred fifty-six".