21242875728 has 80 divisors (see below), whose sum is σ = 56132139456. Its totient is φ = 6920110080.

The previous prime is 21242875699. The next prime is 21242875741. The reversal of 21242875728 is 82757824212.

It is a Harshad number since it is a multiple of its sum of digits (48).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 637563 + ... + 670053.

Almost surely, 2^21242875728 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 21242875728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28066069728).

21242875728 is an abundant number, since it is smaller than the sum of its proper divisors (34889263728).

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

21242875728 is a wasteful number, since it uses less digits than its factorization.

21242875728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 32812 (or 32806 counting only the distinct ones).

The product of its digits is 1003520, while the sum is 48.

The spelling of 21242875728 in words is "twenty-one billion, two hundred forty-two million, eight hundred seventy-five thousand, seven hundred twenty-eight".