21211155125 has 8 divisors (see below), whose sum is σ = 26471521752. Its totient is φ = 16968924000.

The previous prime is 21211155113. The next prime is 21211155139. The reversal of 21211155125 is 52155111212.

It can be written as a sum of positive squares in 4 ways, for example, as 309513649 + 20901641476 = 17593^2 + 144574^2 .

It is not a de Polignac number, because 21211155125 - 2²⁴ = 21194377909 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21211155094 and 21211155103.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 84844496 + ... + 84844745.

It is an arithmetic number, because the mean of its divisors is an integer number (3308940219).

Almost surely, 2^21211155125 is an apocalyptic number.

21211155125 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21211155125 is a deficient number, since it is larger than the sum of its proper divisors (5260366627).

21211155125 is an equidigital number, since it uses as much as digits as its factorization.

21211155125 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 169689256 (or 169689246 counting only the distinct ones).

The product of its digits is 1000, while the sum is 26.

Adding to 21211155125 its reverse (52155111212), we get a palindrome (73366266337).

The spelling of 21211155125 in words is "twenty-one billion, two hundred eleven million, one hundred fifty-five thousand, one hundred twenty-five".