21131333215 has 4 divisors (see below), whose sum is σ = 25357599864. Its totient is φ = 16905066568.

The previous prime is 21131333207. The next prime is 21131333219. The reversal of 21131333215 is 51233313112.

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

It is a cyclic number.

It is not a de Polignac number, because 21131333215 - 2³ = 21131333207 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 21131333215.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21131333219) 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, 2113133317 + ... + 2113133326.

It is an arithmetic number, because the mean of its divisors is an integer number (6339399966).

Almost surely, 2^21131333215 is an apocalyptic number.

21131333215 is a deficient number, since it is larger than the sum of its proper divisors (4226266649).

21131333215 is an equidigital number, since it uses as much as digits as its factorization.

21131333215 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4226266648.

The product of its digits is 1620, while the sum is 25.

Adding to 21131333215 its reverse (51233313112), we get a palindrome (72364646327).

The spelling of 21131333215 in words is "twenty-one billion, one hundred thirty-one million, three hundred thirty-three thousand, two hundred fifteen".