21735997571820 has 288 divisors, whose sum is σ = 74997868377600. Its totient is φ = 4673729034240.

The previous prime is 21735997571807. The next prime is 21735997571831. The reversal of 21735997571820 is 2817579953712.

21735997571820 is digitally balanced in base 5, because in such base it contains all the possibile digits an equal number of times.

It is a super-2 number, since 2×21735997571820² (a number of 27 digits) contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 104804425 + ... + 105011615.

It is an arithmetic number, because the mean of its divisors is an integer number (260409265200).

Almost surely, 2^{21735997571820} is an apocalyptic number.

21735997571820 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 21735997571820, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37498934188800).

21735997571820 is an abundant number, since it is smaller than the sum of its proper divisors (53261870805780).

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

21735997571820 is a wasteful number, since it uses less digits than its factorization.

21735997571820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 209333 (or 209324 counting only the distinct ones).

The product of its (nonzero) digits is 66679200, while the sum is 66.

The spelling of 21735997571820 in words is "twenty-one trillion, seven hundred thirty-five billion, nine hundred ninety-seven million, five hundred seventy-one thousand, eight hundred twenty".