21728798 has 16 divisors (see below), whose sum is σ = 40115040. Its totient is φ = 8595936.

The previous prime is 21728789. The next prime is 21728807. The reversal of 21728798 is 89782712.

It is an interprime number because it is at equal distance from previous prime (21728789) and next prime (21728807).

It is a Smith number, since the sum of its digits (44) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 59513 + ... + 59876.

It is an arithmetic number, because the mean of its divisors is an integer number (2507190).

Almost surely, 2^21728798 is an apocalyptic number.

21728798 is a deficient number, since it is larger than the sum of its proper divisors (18386242).

21728798 is a wasteful number, since it uses less digits than its factorization.

21728798 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 119411.

The product of its digits is 112896, while the sum is 44.

The square root of 21728798 is about 4661.4158793225. The cubic root of 21728798 is about 279.0477772609.

The spelling of 21728798 in words is "twenty-one million, seven hundred twenty-eight thousand, seven hundred ninety-eight".