21071135281 has 27 divisors (see below), whose sum is σ = 24896673921. Its totient is φ = 17781396864.

The previous prime is 21071135257. The next prime is 21071135339. The reversal of 21071135281 is 18253117012.

The square root of 21071135281 is 145159.

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 7711474225 + 13359661056 = 87815^2 + 115584^2 .

It is not a de Polignac number, because 21071135281 - 2¹¹ = 21071133233 is a prime.

It is a super-2 number, since 2×21071135281² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21071135681) 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, 90433941 + ... + 90434173.

Almost surely, 2^21071135281 is an apocalyptic number.

21071135281 is the 145159-th square number.

21071135281 is the 72580-th centered octagonal number.

It is an amenable number.

21071135281 is a deficient number, since it is larger than the sum of its proper divisors (3825538640).

21071135281 is an frugal number, since it uses more digits than its factorization.

21071135281 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 658 (or 329 counting only the distinct ones).

The product of its (nonzero) digits is 3360, while the sum is 31.

The spelling of 21071135281 in words is "twenty-one billion, seventy-one million, one hundred thirty-five thousand, two hundred eighty-one".