28404385 has 4 divisors (see below), whose sum is σ = 34085268. Its totient is φ = 22723504.

The previous prime is 28404377. The next prime is 28404407. The reversal of 28404385 is 58340482.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 58340482 = 2 ⋅29170241.

It can be written as a sum of positive squares in 2 ways, for example, as 14386849 + 14017536 = 3793^2 + 3744^2 .

It is a cyclic number.

It is not a de Polignac number, because 28404385 - 2³ = 28404377 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 28404385.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2840434 + ... + 2840443.

It is an arithmetic number, because the mean of its divisors is an integer number (8521317).

Almost surely, 2^28404385 is an apocalyptic number.

It is an amenable number.

28404385 is a deficient number, since it is larger than the sum of its proper divisors (5680883).

28404385 is an equidigital number, since it uses as much as digits as its factorization.

28404385 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5680882.

The product of its (nonzero) digits is 30720, while the sum is 34.

The square root of 28404385 is about 5329.5764372040. The cubic root of 28404385 is about 305.1137620954.

It can be divided in two parts, 2840 and 4385, that added together give a square (7225 = 85²).

The spelling of 28404385 in words is "twenty-eight million, four hundred four thousand, three hundred eighty-five".