21000726849025 has 81 divisors (see below), whose sum is σ = 33299487181443. Its totient is φ = 13090262354400.

The previous prime is 21000726849023. The next prime is 21000726849061. The reversal of 21000726849025 is 52094862700012.

The square root of 21000726849025 is 4582655.

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

It can be written as a sum of positive squares in only one way, i.e., 7560261665649 + 13440465183376 = 2749593^2 + 3666124^2 .

It is not a de Polignac number, because 21000726849025 - 2¹ = 21000726849023 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21000726849023) by changing a digit.

It is a polite number, since it can be written in 80 ways as a sum of consecutive naturals, for example, 1764316224 + ... + 1764328126.

Almost surely, 2^{21000726849025} is an apocalyptic number.

21000726849025 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21000726849025 is the 4582655-th square number.

21000726849025 is the 2291328-th centered octagonal number.

It is an amenable number.

21000726849025 is a deficient number, since it is larger than the sum of its proper divisors (12298760332418).

21000726849025 is an frugal number, since it uses more digits than its factorization.

21000726849025 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23852 (or 11926 counting only the distinct ones).

The product of its (nonzero) digits is 483840, while the sum is 46.

The spelling of 21000726849025 in words is "twenty-one trillion, seven hundred twenty-six million, eight hundred forty-nine thousand, twenty-five".