21606123431 has 6 divisors (see below), whose sum is σ = 22376854032. Its totient is φ = 20861083880.

The previous prime is 21606123419. The next prime is 21606123449. The reversal of 21606123431 is 13432160612.

It is not a de Polignac number, because 21606123431 - 2²² = 21601929127 is a prime.

It is a super-2 number, since 2×21606123431² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (29).

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21606123394 and 21606123403.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21606128431) 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 5 ways as a sum of consecutive naturals, for example, 12844655 + ... + 12846336.

It is an arithmetic number, because the mean of its divisors is an integer number (3729475672).

Almost surely, 2^21606123431 is an apocalyptic number.

21606123431 is a deficient number, since it is larger than the sum of its proper divisors (770730601).

21606123431 is an equidigital number, since it uses as much as digits as its factorization.

21606123431 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25691049 (or 25691020 counting only the distinct ones).

The product of its (nonzero) digits is 5184, while the sum is 29.

The spelling of 21606123431 in words is "twenty-one billion, six hundred six million, one hundred twenty-three thousand, four hundred thirty-one".