28517281 has 4 divisors (see below), whose sum is σ = 30710932. Its totient is φ = 26323632.

The previous prime is 28517273. The next prime is 28517287. The reversal of 28517281 is 18271582.

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 4064256 + 24453025 = 2016^2 + 4945^2 .

It is a cyclic number.

It is not a de Polignac number, because 28517281 - 2³ = 28517273 is a prime.

It is a super-2 number, since 2×28517281² = 1626470631265922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28517287) 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, 1096806 + ... + 1096831.

It is an arithmetic number, because the mean of its divisors is an integer number (7677733).

Almost surely, 2^28517281 is an apocalyptic number.

It is an amenable number.

28517281 is a deficient number, since it is larger than the sum of its proper divisors (2193651).

28517281 is a wasteful number, since it uses less digits than its factorization.

28517281 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2193650.

The product of its digits is 8960, while the sum is 34.

The square root of 28517281 is about 5340.1573946842. The cubic root of 28517281 is about 305.5174625252.

The spelling of 28517281 in words is "twenty-eight million, five hundred seventeen thousand, two hundred eighty-one".