21031131123 has 12 divisors (see below), whose sum is σ = 30486412008. Its totient is φ = 13970856480.

The previous prime is 21031131067. The next prime is 21031131169. The reversal of 21031131123 is 32113113012.

21031131123 is a `hidden beast` number, since 21 + 0 + 311 + 311 + 23 = 666.

It is not a de Polignac number, because 21031131123 - 2¹² = 21031127027 is a prime.

It is a super-2 number, since 2×21031131123² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21031131096 and 21031131105.

It is not an unprimeable number, because it can be changed into a prime (21031135123) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 4155465 + ... + 4160522.

It is an arithmetic number, because the mean of its divisors is an integer number (2540534334).

Almost surely, 2^21031131123 is an apocalyptic number.

21031131123 is a deficient number, since it is larger than the sum of its proper divisors (9455280885).

21031131123 is a wasteful number, since it uses less digits than its factorization.

21031131123 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8316274 (or 8316271 counting only the distinct ones).

The product of its (nonzero) digits is 108, while the sum is 18.

Adding to 21031131123 its reverse (32113113012), we get a palindrome (53144244135).

The spelling of 21031131123 in words is "twenty-one billion, thirty-one million, one hundred thirty-one thousand, one hundred twenty-three".