21402721720800 has 1728 divisors, whose sum is σ = 91692881280000. Its totient is φ = 4691370700800.

The previous prime is 21402721720799. The next prime is 21402721720811. The reversal of 21402721720800 is 802712720412.

21402721720800 is a `hidden beast` number, since 2 + 1 + 402 + 7 + 2 + 172 + 0 + 80 + 0 = 666.

It is a super-2 number, since 2×21402721720800² (a number of 27 digits) contains 22 as substring.

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 polite number, since it can be written in 287 ways as a sum of consecutive naturals, for example, 6487637551 + ... + 6487640849.

It is an arithmetic number, because the mean of its divisors is an integer number (53063010000).

Almost surely, 2^{21402721720800} is an apocalyptic number.

21402721720800 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 21402721720800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (45846440640000).

21402721720800 is an abundant number, since it is smaller than the sum of its proper divisors (70290159559200).

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

21402721720800 is a wasteful number, since it uses less digits than its factorization.

21402721720800 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3454 (or 3424 counting only the distinct ones).

The product of its (nonzero) digits is 25088, while the sum is 36.

The spelling of 21402721720800 in words is "twenty-one trillion, four hundred two billion, seven hundred twenty-one million, seven hundred twenty thousand, eight hundred".