21251165053 has 4 divisors (see below), whose sum is σ = 21446129980. Its totient is φ = 21056200128.

The previous prime is 21251165029. The next prime is 21251165071. The reversal of 21251165053 is 35056115212.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 13833993924 + 7417171129 = 117618^2 + 86123^2 .

It is a cyclic number.

It is not a de Polignac number, because 21251165053 - 2⁵ = 21251165021 is a prime.

It is a super-2 number, since 2×21251165053² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21251165083) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 97482300 + ... + 97482517.

It is an arithmetic number, because the mean of its divisors is an integer number (5361532495).

Almost surely, 2^21251165053 is an apocalyptic number.

It is an amenable number.

21251165053 is a deficient number, since it is larger than the sum of its proper divisors (194964927).

21251165053 is a wasteful number, since it uses less digits than its factorization.

21251165053 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 194964926.

The product of its (nonzero) digits is 9000, while the sum is 31.

The spelling of 21251165053 in words is "twenty-one billion, two hundred fifty-one million, one hundred sixty-five thousand, fifty-three".