28781185 has 4 divisors (see below), whose sum is σ = 34537428. Its totient is φ = 23024944.

The previous prime is 28781183. The next prime is 28781209. The reversal of 28781185 is 58118782.

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 2903616 + 25877569 = 1704^2 + 5087^2 .

It is a cyclic number.

It is not a de Polignac number, because 28781185 - 2¹ = 28781183 is a prime.

It is a super-2 number, since 2×28781185² = 1656713220008450, which contains 22 as substring.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28781183) 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, 2878114 + ... + 2878123.

It is an arithmetic number, because the mean of its divisors is an integer number (8634357).

Almost surely, 2^28781185 is an apocalyptic number.

It is an amenable number.

28781185 is a deficient number, since it is larger than the sum of its proper divisors (5756243).

28781185 is an equidigital number, since it uses as much as digits as its factorization.

28781185 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5756242.

The product of its digits is 35840, while the sum is 40.

The square root of 28781185 is about 5364.8098754756. The cubic root of 28781185 is about 306.4570078978.

The spelling of 28781185 in words is "twenty-eight million, seven hundred eighty-one thousand, one hundred eighty-five".