21724055920 has 240 divisors, whose sum is σ = 59870596608. Its totient is φ = 7329772800.

The previous prime is 21724055909. The next prime is 21724055989. The reversal of 21724055920 is 2955042712.

It is a self number, because there is not a number n which added to its sum of digits gives 21724055920.

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 47 ways as a sum of consecutive naturals, for example, 143867845 + ... + 143867995.

Almost surely, 2^21724055920 is an apocalyptic number.

21724055920 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 21724055920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29935298304).

21724055920 is an abundant number, since it is smaller than the sum of its proper divisors (38146540688).

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

21724055920 is an equidigital number, since it uses as much as digits as its factorization.

21724055920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 306 (or 272 counting only the distinct ones).

The product of its (nonzero) digits is 50400, while the sum is 37.

The spelling of 21724055920 in words is "twenty-one billion, seven hundred twenty-four million, fifty-five thousand, nine hundred twenty".