21238978124 has 96 divisors (see below), whose sum is σ = 47687270400. Its totient is φ = 8050049280.

The previous prime is 21238978099. The next prime is 21238978139. The reversal of 21238978124 is 42187983212.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1375157 + ... + 1390515.

It is an arithmetic number, because the mean of its divisors is an integer number (496742400).

Almost surely, 2^21238978124 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 21238978124, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23843635200).

21238978124 is an abundant number, since it is smaller than the sum of its proper divisors (26448292276).

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

21238978124 is a wasteful number, since it uses less digits than its factorization.

21238978124 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15543 (or 15541 counting only the distinct ones).

The product of its digits is 387072, while the sum is 47.

The spelling of 21238978124 in words is "twenty-one billion, two hundred thirty-eight million, nine hundred seventy-eight thousand, one hundred twenty-four".