21431423421 has 16 divisors (see below), whose sum is σ = 31752545920. Its totient is φ = 14286585600.

The previous prime is 21431423413. The next prime is 21431423441. The reversal of 21431423421 is 12432413412.

21431423421 is a `hidden beast` number, since 2 + 1 + 4 + 314 + 2 + 342 + 1 = 666.

It is not a de Polignac number, because 21431423421 - 2³ = 21431423413 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21431423441) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 621021 + ... + 654621.

It is an arithmetic number, because the mean of its divisors is an integer number (1984534120).

Almost surely, 2^21431423421 is an apocalyptic number.

It is an amenable number.

21431423421 is a deficient number, since it is larger than the sum of its proper divisors (10321122499).

21431423421 is a wasteful number, since it uses less digits than its factorization.

21431423421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 57233 (or 57227 counting only the distinct ones).

The product of its digits is 4608, while the sum is 27.

Adding to 21431423421 its reverse (12432413412), we get a palindrome (33863836833).

The spelling of 21431423421 in words is "twenty-one billion, four hundred thirty-one million, four hundred twenty-three thousand, four hundred twenty-one".