21123131221423 has 8 divisors (see below), whose sum is σ = 26335332432000. Its totient is φ = 16459582769880.

The previous prime is 21123131221343. The next prime is 21123131221427. The reversal of 21123131221423 is 32412213132112.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21123131221423 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21123131221391 and 21123131221400.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21123131221427) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 137163189673 + ... + 137163189826.

It is an arithmetic number, because the mean of its divisors is an integer number (3291916554000).

Almost surely, 2^{21123131221423} is an apocalyptic number.

21123131221423 is a deficient number, since it is larger than the sum of its proper divisors (5212201210577).

21123131221423 is a wasteful number, since it uses less digits than its factorization.

21123131221423 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 274326379517.

The product of its digits is 3456, while the sum is 28.

Adding to 21123131221423 its reverse (32412213132112), we get a palindrome (53535344353535).

The spelling of 21123131221423 in words is "twenty-one trillion, one hundred twenty-three billion, one hundred thirty-one million, two hundred twenty-one thousand, four hundred twenty-three".