28550881 has 4 divisors (see below), whose sum is σ = 28582164. Its totient is φ = 28519600.

The previous prime is 28550869. The next prime is 28550887. The reversal of 28550881 is 18805582.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 10784656 + 17766225 = 3284^2 + 4215^2 .

It is a cyclic number.

It is not a de Polignac number, because 28550881 - 2⁵ = 28550849 is a prime.

It is a super-2 number, since 2×28550881² = 1630305611752322, which contains 22 as substring.

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 28550881.

It is not an unprimeable number, because it can be changed into a prime (28550887) 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, 14230 + ... + 16111.

It is an arithmetic number, because the mean of its divisors is an integer number (7145541).

Almost surely, 2^28550881 is an apocalyptic number.

It is an amenable number.

28550881 is a deficient number, since it is larger than the sum of its proper divisors (31283).

28550881 is an equidigital number, since it uses as much as digits as its factorization.

28550881 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31282.

The product of its (nonzero) digits is 25600, while the sum is 37.

The square root of 28550881 is about 5343.3024432461. The cubic root of 28550881 is about 305.6374056771.

The spelling of 28550881 in words is "twenty-eight million, five hundred fifty thousand, eight hundred eighty-one".