21215788776 has 384 divisors, whose sum is σ = 72687014400. Its totient is φ = 5441955840.

The previous prime is 21215788751. The next prime is 21215788801. The reversal of 21215788776 is 67788751212.

It is an interprime number because it is at equal distance from previous prime (21215788751) and next prime (21215788801).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 43564005 + ... + 43564491.

It is an arithmetic number, because the mean of its divisors is an integer number (189289100).

Almost surely, 2^21215788776 is an apocalyptic number.

21215788776 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21215788776, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36343507200).

21215788776 is an abundant number, since it is smaller than the sum of its proper divisors (51471225624).

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

21215788776 is a wasteful number, since it uses less digits than its factorization.

21215788776 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 689 (or 682 counting only the distinct ones).

The product of its digits is 2634240, while the sum is 54.

The spelling of 21215788776 in words is "twenty-one billion, two hundred fifteen million, seven hundred eighty-eight thousand, seven hundred seventy-six".