21504672720 has 320 divisors, whose sum is σ = 80490086400. Its totient is φ = 5257198080.

The previous prime is 21504672697. The next prime is 21504672757. The reversal of 21504672720 is 2727640512.

It is a happy number.

21504672720 is a `hidden beast` number, since 2 + 150 + 467 + 27 + 20 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 1263789 + ... + 1280691.

It is an arithmetic number, because the mean of its divisors is an integer number (251531520).

Almost surely, 2^21504672720 is an apocalyptic number.

21504672720 is a gapful number since it is divisible by the number (20) 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 21504672720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (40245043200).

21504672720 is an abundant number, since it is smaller than the sum of its proper divisors (58985413680).

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

21504672720 is a wasteful number, since it uses less digits than its factorization.

21504672720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16975 (or 16963 counting only the distinct ones).

The product of its (nonzero) digits is 47040, while the sum is 36.

The spelling of 21504672720 in words is "twenty-one billion, five hundred four million, six hundred seventy-two thousand, seven hundred twenty".