21180683520 has 720 divisors, whose sum is σ = 81976034448. Its totient is φ = 5202247680.

The previous prime is 21180683519. The next prime is 21180683549. The reversal of 21180683520 is 2538608112.

It is a happy number.

It can be written as a sum of positive squares in 8 ways, for example, as 195105024 + 20985578496 = 13968^2 + 144864^2 .

It is a tau number, because it is divible by the number of its divisors (720).

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

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 107516062 + ... + 107516258.

Almost surely, 2^21180683520 is an apocalyptic number.

21180683520 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 21180683520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (40988017224).

21180683520 is an abundant number, since it is smaller than the sum of its proper divisors (60795350928).

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

21180683520 is a wasteful number, since it uses less digits than its factorization.

21180683520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 308 (or 285 counting only the distinct ones).

The product of its (nonzero) digits is 23040, while the sum is 36.

The spelling of 21180683520 in words is "twenty-one billion, one hundred eighty million, six hundred eighty-three thousand, five hundred twenty".