28281985 has 4 divisors (see below), whose sum is σ = 33938388. Its totient is φ = 22625584.

The previous prime is 28281971. The next prime is 28281991. The reversal of 28281985 is 58918282.

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 3111696 + 25170289 = 1764^2 + 5017^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-28281985 is a prime.

It is a Duffinian 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, 2828194 + ... + 2828203.

It is an arithmetic number, because the mean of its divisors is an integer number (8484597).

Almost surely, 2^28281985 is an apocalyptic number.

It is an amenable number.

28281985 is a deficient number, since it is larger than the sum of its proper divisors (5656403).

28281985 is an equidigital number, since it uses as much as digits as its factorization.

28281985 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5656402.

The product of its digits is 92160, while the sum is 43.

The square root of 28281985 is about 5318.0809508694. The cubic root of 28281985 is about 304.6748662831.

The spelling of 28281985 in words is "twenty-eight million, two hundred eighty-one thousand, nine hundred eighty-five".