21101131123 has 4 divisors (see below), whose sum is σ = 21113867320. Its totient is φ = 21088394928.

The previous prime is 21101131111. The next prime is 21101131127. The reversal of 21101131123 is 32113110112.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21101131123 is a prime.

It is a super-2 number, since 2×21101131123² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21101131097 and 21101131106.

It is not an unprimeable number, because it can be changed into a prime (21101131127) 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, 6365613 + ... + 6368926.

It is an arithmetic number, because the mean of its divisors is an integer number (5278466830).

Almost surely, 2^21101131123 is an apocalyptic number.

21101131123 is a deficient number, since it is larger than the sum of its proper divisors (12736197).

21101131123 is a wasteful number, since it uses less digits than its factorization.

21101131123 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12736196.

The product of its (nonzero) digits is 36, while the sum is 16.

Adding to 21101131123 its reverse (32113110112), we get a palindrome (53214241235).

The spelling of 21101131123 in words is "twenty-one billion, one hundred one million, one hundred thirty-one thousand, one hundred twenty-three".