21309972480 has 336 divisors, whose sum is σ = 76641771024. Its totient is φ = 5680005120.

The previous prime is 21309972479. The next prime is 21309972487. The reversal of 21309972480 is 8427990312.

21309972480 is a `hidden beast` number, since 2 + 13 + 0 + 99 + 72 + 480 = 666.

It is a super-2 number, since 2×21309972480² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21309972487) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 9952210 + ... + 9954350.

It is an arithmetic number, because the mean of its divisors is an integer number (228100509).

Almost surely, 2^21309972480 is an apocalyptic number.

21309972480 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 21309972480, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38320885512).

21309972480 is an abundant number, since it is smaller than the sum of its proper divisors (55331798544).

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

21309972480 is an frugal number, since it uses more digits than its factorization.

21309972480 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2187 (or 2151 counting only the distinct ones).

The product of its (nonzero) digits is 217728, while the sum is 45.

The spelling of 21309972480 in words is "twenty-one billion, three hundred nine million, nine hundred seventy-two thousand, four hundred eighty".