21799728 has 60 divisors (see below), whose sum is σ = 62326368. Its totient is φ = 7109760.

The previous prime is 21799711. The next prime is 21799747. The reversal of 21799728 is 82799712.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 5158 + ... + 8378.

Almost surely, 2^21799728 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 21799728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31163184).

21799728 is an abundant number, since it is smaller than the sum of its proper divisors (40526640).

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

21799728 is a wasteful number, since it uses less digits than its factorization.

21799728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3282 (or 3273 counting only the distinct ones).

The product of its digits is 127008, while the sum is 45.

The square root of 21799728 is about 4669.0178838809. The cubic root of 21799728 is about 279.3510822880.

The spelling of 21799728 in words is "twenty-one million, seven hundred ninety-nine thousand, seven hundred twenty-eight".