21508163712 has 256 divisors, whose sum is σ = 72931795200. Its totient is φ = 6112641024.

The previous prime is 21508163671. The next prime is 21508163713. The reversal of 21508163712 is 21736180512.

21508163712 is a `hidden beast` number, since 2 + 1 + 5 + 0 + 8 + 1 + 637 + 12 = 666.

It is a super-2 number, since 2×21508163712² (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 not an unprimeable number, because it can be changed into a prime (21508163713) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 4763568 + ... + 4768080.

It is an arithmetic number, because the mean of its divisors is an integer number (284889825).

Almost surely, 2^21508163712 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 21508163712, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36465897600).

21508163712 is an abundant number, since it is smaller than the sum of its proper divisors (51423631488).

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

21508163712 is a wasteful number, since it uses less digits than its factorization.

21508163712 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4740 (or 4722 counting only the distinct ones).

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

The spelling of 21508163712 in words is "twenty-one billion, five hundred eight million, one hundred sixty-three thousand, seven hundred twelve".