21131105 has 4 divisors (see below), whose sum is σ = 25357332. Its totient is φ = 16904880.

The previous prime is 21131087. The next prime is 21131137. The reversal of 21131105 is 50113112.

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 6599761 + 14531344 = 2569^2 + 3812^2 .

It is not a de Polignac number, because 21131105 - 2⁶ = 21131041 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21131105.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2113106 + ... + 2113115.

It is an arithmetic number, because the mean of its divisors is an integer number (6339333).

Almost surely, 2^21131105 is an apocalyptic number.

It is an amenable number.

21131105 is a deficient number, since it is larger than the sum of its proper divisors (4226227).

21131105 is an equidigital number, since it uses as much as digits as its factorization.

21131105 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4226226.

The product of its (nonzero) digits is 30, while the sum is 14.

The square root of 21131105 is about 4596.8581661826. The cubic root of 21131105 is about 276.4653678392.

Adding to 21131105 its reverse (50113112), we get a palindrome (71244217).

The spelling of 21131105 in words is "twenty-one million, one hundred thirty-one thousand, one hundred five".