28942409 has 4 divisors (see below), whose sum is σ = 28953216. Its totient is φ = 28931604.

The previous prime is 28942393. The next prime is 28942429. The reversal of 28942409 is 90424982.

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, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 90424982 = 2 ⋅45212491.

It is a cyclic number.

It is not a de Polignac number, because 28942409 - 2⁴ = 28942393 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28942429) by changing a digit.

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 in 3 ways as a sum of consecutive naturals, for example, 1952 + ... + 7854.

It is an arithmetic number, because the mean of its divisors is an integer number (7238304).

Almost surely, 2^28942409 is an apocalyptic number.

It is an amenable number.

28942409 is a deficient number, since it is larger than the sum of its proper divisors (10807).

28942409 is an equidigital number, since it uses as much as digits as its factorization.

28942409 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10806.

The product of its (nonzero) digits is 41472, while the sum is 38.

The square root of 28942409 is about 5379.8149596431. The cubic root of 28942409 is about 307.0281710118.

The spelling of 28942409 in words is "twenty-eight million, nine hundred forty-two thousand, four hundred nine".