21180732720 has 160 divisors (see below), whose sum is σ = 75114144768. Its totient is φ = 4836547584.

The previous prime is 21180732719. The next prime is 21180732737. The reversal of 21180732720 is 2723708112.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1870917 + ... + 1882203.

Almost surely, 2^21180732720 is an apocalyptic number.

21180732720 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 21180732720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37557072384).

21180732720 is an abundant number, since it is smaller than the sum of its proper divisors (53933412048).

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

21180732720 is a wasteful number, since it uses less digits than its factorization.

21180732720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12427 (or 12421 counting only the distinct ones).

The product of its (nonzero) digits is 9408, while the sum is 33.

The spelling of 21180732720 in words is "twenty-one billion, one hundred eighty million, seven hundred thirty-two thousand, seven hundred twenty".