21615544111231 has 4 divisors (see below), whose sum is σ = 24703478984272. Its totient is φ = 18527609238192.

The previous prime is 21615544111181. The next prime is 21615544111267. The reversal of 21615544111231 is 13211144551612.

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 21615544111231 - 2⁷ = 21615544111103 is a prime.

It is a super-2 number, since 2×21615544111231² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21615544111631) 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, 1543967436510 + ... + 1543967436523.

It is an arithmetic number, because the mean of its divisors is an integer number (6175869746068).

Almost surely, 2^{21615544111231} is an apocalyptic number.

21615544111231 is a deficient number, since it is larger than the sum of its proper divisors (3087934873041).

21615544111231 is an equidigital number, since it uses as much as digits as its factorization.

21615544111231 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3087934873040.

The product of its digits is 28800, while the sum is 37.

Adding to 21615544111231 its reverse (13211144551612), we get a palindrome (34826688662843).

The spelling of 21615544111231 in words is "twenty-one trillion, six hundred fifteen billion, five hundred forty-four million, one hundred eleven thousand, two hundred thirty-one".