28520117 has 4 divisors (see below), whose sum is σ = 29126976. Its totient is φ = 27913260.

The previous prime is 28520111. The next prime is 28520119. The reversal of 28520117 is 71102582.

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 an emirpimes, since its reverse is a distinct semiprime: 71102582 = 2 ⋅35551291.

It is a cyclic number.

It is not a de Polignac number, because 28520117 - 2¹⁶ = 28454581 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28520111) 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, 303359 + ... + 303452.

It is an arithmetic number, because the mean of its divisors is an integer number (7281744).

Almost surely, 2^28520117 is an apocalyptic number.

It is an amenable number.

28520117 is a deficient number, since it is larger than the sum of its proper divisors (606859).

28520117 is an equidigital number, since it uses as much as digits as its factorization.

28520117 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 606858.

The product of its (nonzero) digits is 1120, while the sum is 26.

The square root of 28520117 is about 5340.4229233273. The cubic root of 28520117 is about 305.5275899376.

Adding to 28520117 its reverse (71102582), we get a palindrome (99622699).

It can be divided in two parts, 285 and 20117, that added together give a palindrome (20402).

The spelling of 28520117 in words is "twenty-eight million, five hundred twenty thousand, one hundred seventeen".