28456409 has 4 divisors (see below), whose sum is σ = 28468404. Its totient is φ = 28444416.

The previous prime is 28456399. The next prime is 28456423. The reversal of 28456409 is 90465482.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 90465482 = 2 ⋅45232741.

It can be written as a sum of positive squares in 2 ways, for example, as 18088009 + 10368400 = 4253^2 + 3220^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-28456409 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28456469) 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, 1112 + ... + 7625.

It is an arithmetic number, because the mean of its divisors is an integer number (7117101).

Almost surely, 2^28456409 is an apocalyptic number.

It is an amenable number.

28456409 is a deficient number, since it is larger than the sum of its proper divisors (11995).

28456409 is an equidigital number, since it uses as much as digits as its factorization.

28456409 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11994.

The product of its (nonzero) digits is 69120, while the sum is 38.

The square root of 28456409 is about 5334.4548924890. The cubic root of 28456409 is about 305.2999253391.

The spelling of 28456409 in words is "twenty-eight million, four hundred fifty-six thousand, four hundred nine".