21118909056 has 384 divisors, whose sum is σ = 69874047360. Its totient is φ = 5615124480.

The previous prime is 21118909043. The next prime is 21118909067. The reversal of 21118909056 is 65090981112.

It is a tau number, because it is divible by the number of its divisors (384).

It is a super-2 number, since 2×21118909056² (a number of 21 digits) contains 22 as substring.

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 = 21118908999 and 21118909017.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 32946496 + ... + 32947136.

It is an arithmetic number, because the mean of its divisors is an integer number (181963665).

Almost surely, 2^21118909056 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 21118909056, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34937023680).

21118909056 is an abundant number, since it is smaller than the sum of its proper divisors (48755138304).

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

21118909056 is a wasteful number, since it uses less digits than its factorization.

21118909056 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 792 (or 773 counting only the distinct ones).

The product of its (nonzero) digits is 38880, while the sum is 42.

The spelling of 21118909056 in words is "twenty-one billion, one hundred eighteen million, nine hundred nine thousand, fifty-six".