28820409 has 4 divisors (see below), whose sum is σ = 38427216. Its totient is φ = 19213604.

The previous prime is 28820401. The next prime is 28820411. The reversal of 28820409 is 90402882.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 28820409 - 2³ = 28820401 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 28820409.

It is not an unprimeable number, because it can be changed into a prime (28820401) 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, 4803399 + ... + 4803404.

It is an arithmetic number, because the mean of its divisors is an integer number (9606804).

Almost surely, 2^28820409 is an apocalyptic number.

It is an amenable number.

28820409 is a deficient number, since it is larger than the sum of its proper divisors (9606807).

28820409 is an equidigital number, since it uses as much as digits as its factorization.

28820409 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9606806.

The product of its (nonzero) digits is 9216, while the sum is 33.

The square root of 28820409 is about 5368.4643055533. The cubic root of 28820409 is about 306.5961614590.

The spelling of 28820409 in words is "twenty-eight million, eight hundred twenty thousand, four hundred nine".