21015768424 has 64 divisors (see below), whose sum is σ = 47724768000. Its totient is φ = 8469494784.

The previous prime is 21015768419. The next prime is 21015768427. The reversal of 21015768424 is 42486751012.

It is not an unprimeable number, because it can be changed into a prime (21015768427) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1145677 + ... + 1163875.

It is an arithmetic number, because the mean of its divisors is an integer number (745699500).

Almost surely, 2^21015768424 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 21015768424, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23862384000).

21015768424 is an abundant number, since it is smaller than the sum of its proper divisors (26708999576).

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

21015768424 is a wasteful number, since it uses less digits than its factorization.

21015768424 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19442 (or 19438 counting only the distinct ones).

The product of its (nonzero) digits is 107520, while the sum is 40.

The spelling of 21015768424 in words is "twenty-one billion, fifteen million, seven hundred sixty-eight thousand, four hundred twenty-four".