28390281 has 4 divisors (see below), whose sum is σ = 37853712. Its totient is φ = 18926852.

The previous prime is 28390267. The next prime is 28390283. The reversal of 28390281 is 18209382.

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.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-28390281 is a prime.

It is a super-2 number, since 2×28390281² = 1612016110517922, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (28390283) 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, 4731711 + ... + 4731716.

It is an arithmetic number, because the mean of its divisors is an integer number (9463428).

Almost surely, 2^28390281 is an apocalyptic number.

It is an amenable number.

28390281 is a deficient number, since it is larger than the sum of its proper divisors (9463431).

28390281 is an equidigital number, since it uses as much as digits as its factorization.

28390281 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9463430.

The product of its (nonzero) digits is 6912, while the sum is 33.

The square root of 28390281 is about 5328.2530908357. The cubic root of 28390281 is about 305.0632530283.

The spelling of 28390281 in words is "twenty-eight million, three hundred ninety thousand, two hundred eighty-one".