21231431040 has 128 divisors (see below), whose sum is σ = 68628798720. Its totient is φ = 5581936640.

The previous prime is 21231431029. The next prime is 21231431069. The reversal of 21231431040 is 4013413212.

It is a tau number, because it is divible by the number of its divisors (128).

It is a junction number, because it is equal to n+sod(n) for n = 21231430998 and 21231431016.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 58447 + ... + 214193.

It is an arithmetic number, because the mean of its divisors is an integer number (536162490).

Almost surely, 2^21231431040 is an apocalyptic number.

21231431040 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 21231431040, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34314399360).

21231431040 is an abundant number, since it is smaller than the sum of its proper divisors (47397367680).

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

21231431040 is a wasteful number, since it uses less digits than its factorization.

21231431040 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 155840 (or 155828 counting only the distinct ones).

The product of its (nonzero) digits is 576, while the sum is 21.

Adding to 21231431040 its reverse (4013413212), we get a palindrome (25244844252).

The spelling of 21231431040 in words is "twenty-one billion, two hundred thirty-one million, four hundred thirty-one thousand, forty".