21249518478400 has 189 divisors, whose sum is σ = 55551926876239. Its totient is φ = 7998638632960.

The previous prime is 21249518478371. The next prime is 21249518478431. The reversal of 21249518478400 is 487481594212.

The square root of 21249518478400 is 4609720.

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 497047560256 + 20752470918144 = 705016^2 + 4555488^2 .

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 3134606211 + ... + 3134612989.

Almost surely, 2^{21249518478400} is an apocalyptic number.

21249518478400 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

21249518478400 is the 4609720-th square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21249518478400

21249518478400 is an abundant number, since it is smaller than the sum of its proper divisors (34302408397839).

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

21249518478400 is an frugal number, since it uses more digits than its factorization.

21249518478400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13614 (or 6803 counting only the distinct ones).

The product of its (nonzero) digits is 5160960, while the sum is 55.

The spelling of 21249518478400 in words is "twenty-one trillion, two hundred forty-nine billion, five hundred eighteen million, four hundred seventy-eight thousand, four hundred".