21112728 has 96 divisors (see below), whose sum is σ = 66170160. Its totient is φ = 5564160.

The previous prime is 21112727. The next prime is 21112733. The reversal of 21112728 is 82721112.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a nude number because it is divisible by every one of its digits.

It is a junction number, because it is equal to n+sod(n) for n = 21112698 and 21112707.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21112723) 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, 14598 + ... + 15978.

Almost surely, 2^21112728 is an apocalyptic number.

21112728 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21112728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33085080).

21112728 is an abundant number, since it is smaller than the sum of its proper divisors (45057432).

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

21112728 is a wasteful number, since it uses less digits than its factorization.

21112728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1417 (or 1406 counting only the distinct ones).

The product of its digits is 448, while the sum is 24.

The square root of 21112728 is about 4594.8588661677. The cubic root of 21112728 is about 276.3852004337.

The spelling of 21112728 in words is "twenty-one million, one hundred twelve thousand, seven hundred twenty-eight".