21001368425625 has 675 divisors, whose sum is σ = 46889571502059. Its totient is φ = 9053998128000.

The previous prime is 21001368425623. The next prime is 21001368425647. The reversal of 21001368425625 is 52652486310012.

The square root of 21001368425625 is 4582725.

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

21001368425625 is a `hidden beast` number, since 2 + 1 + 0 + 0 + 1 + 3 + 6 + 84 + 2 + 562 + 5 = 666.

It can be written as a sum of positive squares in 7 ways, for example, as 15707485313289 + 5293883112336 = 3963267^2 + 2300844^2 .

It is not a de Polignac number, because 21001368425625 - 2¹ = 21001368425623 is a prime.

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

It is not an unprimeable number, because it can be changed into a prime (21001368425623) by changing a digit.

It is a polite number, since it can be written in 674 ways as a sum of consecutive naturals, for example, 488403916854 + ... + 488403916896.

Almost surely, 2^{21001368425625} is an apocalyptic number.

21001368425625 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21001368425625 is the 4582725-th square number.

21001368425625 is the 2291363-rd centered octagonal number.

It is an amenable number.

21001368425625 is an abundant number, since it is smaller than the sum of its proper divisors (25888203076434).

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

21001368425625 is an frugal number, since it uses more digits than its factorization.

21001368425625 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 198 (or 87 counting only the distinct ones).

The product of its (nonzero) digits is 691200, while the sum is 45.

The spelling of 21001368425625 in words is "twenty-one trillion, one billion, three hundred sixty-eight million, four hundred twenty-five thousand, six hundred twenty-five".