28209331 has 6 divisors (see below), whose sum is σ = 28496580. Its totient is φ = 27924948.

The previous prime is 28209329. The next prime is 28209343. The reversal of 28209331 is 13390282.

It is not a de Polignac number, because 28209331 - 2¹ = 28209329 is a prime.

It is a super-2 number, since 2×28209331² = 1591532710935122, 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 28209331.

It is not an unprimeable number, because it can be changed into a prime (28209301) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 9280 + ... + 11938.

It is an arithmetic number, because the mean of its divisors is an integer number (4749430).

Almost surely, 2^28209331 is an apocalyptic number.

28209331 is a deficient number, since it is larger than the sum of its proper divisors (287249).

28209331 is an equidigital number, since it uses as much as digits as its factorization.

28209331 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2865 (or 2762 counting only the distinct ones).

The product of its (nonzero) digits is 2592, while the sum is 28.

The square root of 28209331 is about 5311.2457107537. The cubic root of 28209331 is about 304.4137480027.

The spelling of 28209331 in words is "twenty-eight million, two hundred nine thousand, three hundred thirty-one".