21431111440 has 80 divisors (see below), whose sum is σ = 50641044480. Its totient is φ = 8432990720.

The previous prime is 21431111431. The next prime is 21431111453. The reversal of 21431111440 is 4411113412.

It is a tau number, because it is divible by the number of its divisors (80).

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2716782 + ... + 2724658.

It is an arithmetic number, because the mean of its divisors is an integer number (633013056).

Almost surely, 2^21431111440 is an apocalyptic number.

21431111440 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 21431111440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25320522240).

21431111440 is an abundant number, since it is smaller than the sum of its proper divisors (29209933040).

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

21431111440 is a wasteful number, since it uses less digits than its factorization.

21431111440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8440 (or 8434 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 22.

Adding to 21431111440 its reverse (4411113412), we get a palindrome (25842224852).

The spelling of 21431111440 in words is "twenty-one billion, four hundred thirty-one million, one hundred eleven thousand, four hundred forty".