21423431420 has 72 divisors (see below), whose sum is σ = 48302276064. Its totient is φ = 7975110528.

The previous prime is 21423431401. The next prime is 21423431461. The reversal of 21423431420 is 2413432412.

It is a self number, because there is not a number n which added to its sum of digits gives 21423431420.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 364097 + ... + 418823.

Almost surely, 2^21423431420 is an apocalyptic number.

21423431420 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21423431420, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24151138032).

21423431420 is an abundant number, since it is smaller than the sum of its proper divisors (26878844644).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21423431420 is a wasteful number, since it uses less digits than its factorization.

21423431420 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 54819 (or 54794 counting only the distinct ones).

The product of its (nonzero) digits is 4608, while the sum is 26.

Adding to 21423431420 its reverse (2413432412), we get a palindrome (23836863832).

The spelling of 21423431420 in words is "twenty-one billion, four hundred twenty-three million, four hundred thirty-one thousand, four hundred twenty".