21323425421 has 4 divisors (see below), whose sum is σ = 21353083200. Its totient is φ = 21293767644.

The previous prime is 21323425391. The next prime is 21323425433. The reversal of 21323425421 is 12452432312.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21323425421 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21323425451) 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, 14827811 + ... + 14829248.

It is an arithmetic number, because the mean of its divisors is an integer number (5338270800).

Almost surely, 2^21323425421 is an apocalyptic number.

It is an amenable number.

21323425421 is a deficient number, since it is larger than the sum of its proper divisors (29657779).

21323425421 is an equidigital number, since it uses as much as digits as its factorization.

21323425421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 29657778.

The product of its digits is 11520, while the sum is 29.

Adding to 21323425421 its reverse (12452432312), we get a palindrome (33775857733).

The spelling of 21323425421 in words is "twenty-one billion, three hundred twenty-three million, four hundred twenty-five thousand, four hundred twenty-one".