28466721 has 28 divisors (see below), whose sum is σ = 45210852. Its totient is φ = 17853696.

The previous prime is 28466717. The next prime is 28466723. The reversal of 28466721 is 12766482.

It can be written as a sum of positive squares in 2 ways, for example, as 17969121 + 10497600 = 4239^2 + 3240^2 .

It is not a de Polignac number, because 28466721 - 2² = 28466717 is a prime.

It is not an unprimeable number, because it can be changed into a prime (28466723) by changing a digit.

It is a polite number, since it can be written in 27 ways as a sum of consecutive naturals, for example, 11245 + ... + 13541.

Almost surely, 2^28466721 is an apocalyptic number.

It is an amenable number.

28466721 is a deficient number, since it is larger than the sum of its proper divisors (16744131).

28466721 is an equidigital number, since it uses as much as digits as its factorization.

28466721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2332 (or 2317 counting only the distinct ones).

The product of its digits is 32256, while the sum is 36.

The square root of 28466721 is about 5335.4213516835. The cubic root of 28466721 is about 305.3367989612.

The spelling of 28466721 in words is "twenty-eight million, four hundred sixty-six thousand, seven hundred twenty-one".