28920665 has 4 divisors (see below), whose sum is σ = 34704804. Its totient is φ = 23136528.

The previous prime is 28920607. The next prime is 28920667. The reversal of 28920665 is 56602982.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 13741849 + 15178816 = 3707^2 + 3896^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-28920665 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28920667) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2892062 + ... + 2892071.

It is an arithmetic number, because the mean of its divisors is an integer number (8676201).

Almost surely, 2^28920665 is an apocalyptic number.

It is an amenable number.

28920665 is a deficient number, since it is larger than the sum of its proper divisors (5784139).

28920665 is an equidigital number, since it uses as much as digits as its factorization.

28920665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5784138.

The product of its (nonzero) digits is 51840, while the sum is 38.

The square root of 28920665 is about 5377.7936925843. The cubic root of 28920665 is about 306.9512631875.

The spelling of 28920665 in words is "twenty-eight million, nine hundred twenty thousand, six hundred sixty-five".