21517778304 has 384 divisors, whose sum is σ = 71267938560. Its totient is φ = 6407424000.

The previous prime is 21517778263. The next prime is 21517778377. The reversal of 21517778304 is 40387771512.

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

It is a self number, because there is not a number n which added to its sum of digits gives 21517778304.

It is a congruent number.

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, 20870269 + ... + 20871299.

It is an arithmetic number, because the mean of its divisors is an integer number (185593590).

Almost surely, 2^21517778304 is an apocalyptic number.

21517778304 is a gapful number since it is divisible by the number (24) 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 21517778304, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35633969280).

21517778304 is an abundant number, since it is smaller than the sum of its proper divisors (49750160256).

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

21517778304 is a wasteful number, since it uses less digits than its factorization.

21517778304 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1132 (or 1108 counting only the distinct ones).

The product of its (nonzero) digits is 329280, while the sum is 45.

It can be divided in two parts, 2151777 and 8304, that added together give a triangular number (2160081 = T₂₀₇₈).

The spelling of 21517778304 in words is "twenty-one billion, five hundred seventeen million, seven hundred seventy-eight thousand, three hundred four".