22721728 has 14 divisors (see below), whose sum is σ = 45088556. Its totient is φ = 11360832.

The previous prime is 22721717. The next prime is 22721731. The reversal of 22721728 is 82712722.

It is a self number, because there is not a number n which added to its sum of digits gives 22721728.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 177450 + ... + 177577.

Almost surely, 2^22721728 is an apocalyptic number.

It is an amenable number.

22721728 is a deficient number, since it is larger than the sum of its proper divisors (22366828).

22721728 is an equidigital number, since it uses as much as digits as its factorization.

22721728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 355039 (or 355029 counting only the distinct ones).

The product of its digits is 6272, while the sum is 31.

The square root of 22721728 is about 4766.7313748522. The cubic root of 22721728 is about 283.2351302883.

The spelling of 22721728 in words is "twenty-two million, seven hundred twenty-one thousand, seven hundred twenty-eight".