21728874 has 16 divisors (see below), whose sum is σ = 44195040. Its totient is φ = 7120080.

The previous prime is 21728867. The next prime is 21728891. The reversal of 21728874 is 47882712.

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, 30337 + ... + 31044.

It is an arithmetic number, because the mean of its divisors is an integer number (2762190).

Almost surely, 2^21728874 is an apocalyptic number.

21728874 is an abundant number, since it is smaller than the sum of its proper divisors (22466166).

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

21728874 is a wasteful number, since it uses less digits than its factorization.

21728874 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 61445.

The product of its digits is 50176, while the sum is 39.

The square root of 21728874 is about 4661.4240313449. The cubic root of 21728874 is about 279.0481025988.

The spelling of 21728874 in words is "twenty-one million, seven hundred twenty-eight thousand, eight hundred seventy-four".