21115221231 has 32 divisors (see below), whose sum is σ = 31676359680. Its totient is φ = 12413769984.

The previous prime is 21115221223. The next prime is 21115221247. The reversal of 21115221231 is 13212251112.

It is not a de Polignac number, because 21115221231 - 2³ = 21115221223 is a prime.

It is a super-2 number, since 2×21115221231² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21115221198 and 21115221207.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21115221931) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 738555 + ... + 766611.

It is an arithmetic number, because the mean of its divisors is an integer number (989886240).

Almost surely, 2^21115221231 is an apocalyptic number.

21115221231 is a deficient number, since it is larger than the sum of its proper divisors (10561138449).

21115221231 is a wasteful number, since it uses less digits than its factorization.

21115221231 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28935.

The product of its digits is 240, while the sum is 21.

Adding to 21115221231 its reverse (13212251112), we get a palindrome (34327472343).

The spelling of 21115221231 in words is "twenty-one billion, one hundred fifteen million, two hundred twenty-one thousand, two hundred thirty-one".