21004872924 has 72 divisors (see below), whose sum is σ = 57146197248. Its totient is φ = 5987395680.

The previous prime is 21004872923. The next prime is 21004872929. The reversal of 21004872924 is 42927840012.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21004872923) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 211987 + ... + 294869.

It is an arithmetic number, because the mean of its divisors is an integer number (793697184).

Almost surely, 2^21004872924 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 21004872924, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28573098624).

21004872924 is an abundant number, since it is smaller than the sum of its proper divisors (36141324324).

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

21004872924 is a wasteful number, since it uses less digits than its factorization.

21004872924 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 83335 (or 83326 counting only the distinct ones).

The product of its (nonzero) digits is 64512, while the sum is 39.

The spelling of 21004872924 in words is "twenty-one billion, four million, eight hundred seventy-two thousand, nine hundred twenty-four".