21309765400 has 384 divisors, whose sum is σ = 66052915200. Its totient is φ = 6192806400.

The previous prime is 21309765371. The next prime is 21309765401. The reversal of 21309765400 is 456790312.

It is a super-2 number, since 2×21309765400² (a number of 21 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21309765400.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21309765401) by changing a digit.

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 95 ways as a sum of consecutive naturals, for example, 19603657 + ... + 19604743.

It is an arithmetic number, because the mean of its divisors is an integer number (172012800).

Almost surely, 2^21309765400 is an apocalyptic number.

21309765400 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 21309765400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33026457600).

21309765400 is an abundant number, since it is smaller than the sum of its proper divisors (44743149800).

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

21309765400 is a wasteful number, since it uses less digits than its factorization.

21309765400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1207 (or 1198 counting only the distinct ones).

The product of its (nonzero) digits is 45360, while the sum is 37.

The spelling of 21309765400 in words is "twenty-one billion, three hundred nine million, seven hundred sixty-five thousand, four hundred".