21111451878400 has 495 divisors, whose sum is σ = 57897802747191. Its totient is φ = 7629146603520.

The previous prime is 21111451878367. The next prime is 21111451878421. The reversal of 21111451878400 is 487815411112.

The square root of 21111451878400 is 4594720.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in 4 ways, for example, as 5441507951616 + 15669943926784 = 2332704^2 + 3958528^2 .

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 44 ways as a sum of consecutive naturals, for example, 449179827177 + ... + 449179827223.

Almost surely, 2^{21111451878400} is an apocalyptic number.

21111451878400 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

21111451878400 is the 4594720-th square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21111451878400

21111451878400 is an abundant number, since it is smaller than the sum of its proper divisors (36786350868791).

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

21111451878400 is an frugal number, since it uses more digits than its factorization.

21111451878400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 244 (or 67 counting only the distinct ones).

The product of its (nonzero) digits is 71680, while the sum is 43.

The spelling of 21111451878400 in words is "twenty-one trillion, one hundred eleven billion, four hundred fifty-one million, eight hundred seventy-eight thousand, four hundred".