21061521125 has 8 divisors (see below), whose sum is σ = 26284778520. Its totient is φ = 16849216800.

The previous prime is 21061521113. The next prime is 21061521127. The reversal of 21061521125 is 52112516012.

It can be written as a sum of positive squares in 4 ways, for example, as 320624836 + 20740896289 = 17906^2 + 144017^2 .

It is not a de Polignac number, because 21061521125 - 2³⁴ = 3881651941 is a prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21061521094 and 21061521103.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21061521127) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 84245960 + ... + 84246209.

It is an arithmetic number, because the mean of its divisors is an integer number (3285597315).

Almost surely, 2^21061521125 is an apocalyptic number.

21061521125 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21061521125 is a deficient number, since it is larger than the sum of its proper divisors (5223257395).

21061521125 is an equidigital number, since it uses as much as digits as its factorization.

21061521125 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 168492184 (or 168492174 counting only the distinct ones).

The product of its (nonzero) digits is 1200, while the sum is 26.

The spelling of 21061521125 in words is "twenty-one billion, sixty-one million, five hundred twenty-one thousand, one hundred twenty-five".