21107509792681 has 27 divisors (see below), whose sum is σ = 23012791528293. Its totient is φ = 19351153692000.

The previous prime is 21107509792661. The next prime is 21107509792757. The reversal of 21107509792681 is 18629790570112.

The square root of 21107509792681 is 4594291.

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 6806406170281 + 14301103622400 = 2608909^2 + 3781680^2 .

It is not a de Polignac number, because 21107509792681 - 2¹⁹ = 21107509268393 is a prime.

It is a super-2 number, since 2×21107509792681² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21107509792601) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 9376946806 + ... + 9376949056.

It is an arithmetic number, because the mean of its divisors is an integer number (852325612159).

Almost surely, 2^{21107509792681} is an apocalyptic number.

21107509792681 is the 4594291-st square number.

21107509792681 is the 2297146-th centered octagonal number.

It is an amenable number.

21107509792681 is a deficient number, since it is larger than the sum of its proper divisors (1905281735612).

21107509792681 is an frugal number, since it uses more digits than its factorization.

21107509792681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4842 (or 2421 counting only the distinct ones).

The product of its (nonzero) digits is 3810240, while the sum is 58.

The spelling of 21107509792681 in words is "twenty-one trillion, one hundred seven billion, five hundred nine million, seven hundred ninety-two thousand, six hundred eighty-one".