21220812576 has 72 divisors (see below), whose sum is σ = 60543507024. Its totient is φ = 7050533760.

The previous prime is 21220812559. The next prime is 21220812593. The reversal of 21220812576 is 67521802212.

It is a happy number.

21220812576 is a `hidden beast` number, since 2 + 1 + 2 + 2 + 0 + 81 + 2 + 576 = 666.

It is an interprime number because it is at equal distance from previous prime (21220812559) and next prime (21220812593).

It is a tau number, because it is divible by the number of its divisors (72).

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 21220812576.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 31590 + ... + 208421.

It is an arithmetic number, because the mean of its divisors is an integer number (840882042).

Almost surely, 2^21220812576 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 21220812576, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30271753512).

21220812576 is an abundant number, since it is smaller than the sum of its proper divisors (39322694448).

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

21220812576 is a wasteful number, since it uses less digits than its factorization.

21220812576 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 240334 (or 240323 counting only the distinct ones).

The product of its (nonzero) digits is 26880, while the sum is 36.

The spelling of 21220812576 in words is "twenty-one billion, two hundred twenty million, eight hundred twelve thousand, five hundred seventy-six".