21125238288400 has 135 divisors (see below), whose sum is σ = 51421641890871. Its totient is φ = 8340264042240.

The previous prime is 21125238288389. The next prime is 21125238288461. The reversal of 21125238288400 is 488283252112.

The square root of 21125238288400 is 4596220.

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 1508701237264 + 19616537051136 = 1228292^2 + 4429056^2 .

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 7262026146 + ... + 7262029054.

Almost surely, 2^{21125238288400} is an apocalyptic number.

21125238288400 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

21125238288400 is the 4596220-th square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21125238288400

21125238288400 is an abundant number, since it is smaller than the sum of its proper divisors (30296403602471).

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

21125238288400 is an frugal number, since it uses more digits than its factorization.

21125238288400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5994 (or 2995 counting only the distinct ones).

The product of its (nonzero) digits is 491520, while the sum is 46.

The spelling of 21125238288400 in words is "twenty-one trillion, one hundred twenty-five billion, two hundred thirty-eight million, two hundred eighty-eight thousand, four hundred".