21431423420 has 96 divisors (see below), whose sum is σ = 50511867840. Its totient is φ = 7569469440.

The previous prime is 21431423413. The next prime is 21431423441. The reversal of 21431423420 is 2432413412.

It is a self number, because there is not a number n which added to its sum of digits gives 21431423420.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 5508836 + ... + 5512724.

It is an arithmetic number, because the mean of its divisors is an integer number (526165290).

Almost surely, 2^21431423420 is an apocalyptic number.

21431423420 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 21431423420, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25255933920).

21431423420 is an abundant number, since it is smaller than the sum of its proper divisors (29080444420).

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

21431423420 is a wasteful number, since it uses less digits than its factorization.

21431423420 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4623 (or 4621 counting only the distinct ones).

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

Adding to 21431423420 its reverse (2432413412), we get a palindrome (23863836832).

The spelling of 21431423420 in words is "twenty-one billion, four hundred thirty-one million, four hundred twenty-three thousand, four hundred twenty".