21312631424 has 64 divisors (see below), whose sum is σ = 48653102400. Its totient is φ = 9109739520.

The previous prime is 21312631423. The next prime is 21312631429. The reversal of 21312631424 is 42413621312.

It is a tau number, because it is divible by the number of its divisors (64).

It is not an unprimeable number, because it can be changed into a prime (21312631423) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 308204 + ... + 370964.

It is an arithmetic number, because the mean of its divisors is an integer number (760204725).

Almost surely, 2^21312631424 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21312631424, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24326551200).

21312631424 is an abundant number, since it is smaller than the sum of its proper divisors (27340470976).

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

21312631424 is an equidigital number, since it uses as much as digits as its factorization.

21312631424 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 63161 (or 63149 counting only the distinct ones).

The product of its digits is 6912, while the sum is 29.

The spelling of 21312631424 in words is "twenty-one billion, three hundred twelve million, six hundred thirty-one thousand, four hundred twenty-four".