28251605 has 4 divisors (see below), whose sum is σ = 33901932. Its totient is φ = 22601280.

The previous prime is 28251593. The next prime is 28251617. The reversal of 28251605 is 50615282.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 50615282 = 2 ⋅25307641.

It is an interprime number because it is at equal distance from previous prime (28251593) and next prime (28251617).

It can be written as a sum of positive squares in 2 ways, for example, as 11792356 + 16459249 = 3434^2 + 4057^2 .

It is not a de Polignac number, because 28251605 - 2⁴ = 28251589 is a prime.

It is a Duffinian number.

It is a congruent number.

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, 2825156 + ... + 2825165.

It is an arithmetic number, because the mean of its divisors is an integer number (8475483).

Almost surely, 2^28251605 is an apocalyptic number.

It is an amenable number.

28251605 is a deficient number, since it is larger than the sum of its proper divisors (5650327).

28251605 is an equidigital number, since it uses as much as digits as its factorization.

28251605 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5650326.

The product of its (nonzero) digits is 4800, while the sum is 29.

The square root of 28251605 is about 5315.2238899222. The cubic root of 28251605 is about 304.5657351096.

Adding to 28251605 its reverse (50615282), we get a palindrome (78866887).

The spelling of 28251605 in words is "twenty-eight million, two hundred fifty-one thousand, six hundred five".