21131225105 has 4 divisors (see below), whose sum is σ = 25357470132. Its totient is φ = 16904980080.

The previous prime is 21131225081. The next prime is 21131225107. The reversal of 21131225105 is 50152213112.

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 6127914961 + 15003310144 = 78281^2 + 122488^2 .

It is a de Polignac number, because none of the positive numbers 2^k-21131225105 is a prime.

It is a super-2 number, since 2×21131225105² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21131225107) 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, 2113122506 + ... + 2113122515.

It is an arithmetic number, because the mean of its divisors is an integer number (6339367533).

Almost surely, 2^21131225105 is an apocalyptic number.

It is an amenable number.

21131225105 is a deficient number, since it is larger than the sum of its proper divisors (4226245027).

21131225105 is an equidigital number, since it uses as much as digits as its factorization.

21131225105 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4226245026.

The product of its (nonzero) digits is 600, while the sum is 23.

Adding to 21131225105 its reverse (50152213112), we get a palindrome (71283438217).

The spelling of 21131225105 in words is "twenty-one billion, one hundred thirty-one million, two hundred twenty-five thousand, one hundred five".