21212656718400 has 567 divisors, whose sum is σ = 87720142642041. Its totient is φ = 4847722951680.

The previous prime is 21212656718369. The next prime is 21212656718413. The reversal of 21212656718400 is 481765621212.

The square root of 21212656718400 is 4605720.

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

21212656718400 is a `hidden beast` number, since 2 + 1 + 2 + 1 + 2 + 6 + 567 + 1 + 84 + 0 + 0 = 666.

It can be written as a sum of positive squares in only one way, i.e., 7636556418624 + 13576100299776 = 2763432^2 + 3684576^2 .

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a polite number, since it can be written in 80 ways as a sum of consecutive naturals, for example, 3868802059 + ... + 3868807541.

Almost surely, 2^{21212656718400} is an apocalyptic number.

21212656718400 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

21212656718400 is the 4605720-th square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21212656718400

21212656718400 is an abundant number, since it is smaller than the sum of its proper divisors (66507485923641).

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

21212656718400 is an frugal number, since it uses more digits than its factorization.

21212656718400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11008 (or 5500 counting only the distinct ones).

The product of its (nonzero) digits is 322560, while the sum is 45.

The spelling of 21212656718400 in words is "twenty-one trillion, two hundred twelve billion, six hundred fifty-six million, seven hundred eighteen thousand, four hundred".