21242115531 has 48 divisors (see below), whose sum is σ = 37778657280. Its totient is φ = 11200213440.

The previous prime is 21242115529. The next prime is 21242115569. The reversal of 21242115531 is 13551124212.

It is a happy number.

21242115531 is a `hidden beast` number, since 2 + 12 + 4 + 2 + 115 + 531 = 666.

It is not a de Polignac number, because 21242115531 - 2¹ = 21242115529 is a prime.

It is a super-2 number, since 2×21242115531² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21242115495 and 21242115504.

It is not an unprimeable number, because it can be changed into a prime (21242115511) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 3796546 + ... + 3802136.

It is an arithmetic number, because the mean of its divisors is an integer number (787055360).

Almost surely, 2^21242115531 is an apocalyptic number.

21242115531 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

21242115531 is a deficient number, since it is larger than the sum of its proper divisors (16536541749).

21242115531 is a wasteful number, since it uses less digits than its factorization.

21242115531 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10256 (or 10253 counting only the distinct ones).

The product of its digits is 2400, while the sum is 27.

Adding to 21242115531 its reverse (13551124212), we get a palindrome (34793239743).

The spelling of 21242115531 in words is "twenty-one billion, two hundred forty-two million, one hundred fifteen thousand, five hundred thirty-one".