28239261 has 32 divisors (see below), whose sum is σ = 41564160. Its totient is φ = 16982784.

The previous prime is 28239259. The next prime is 28239271. The reversal of 28239261 is 16293282.

It is a happy number.

It is not a de Polignac number, because 28239261 - 2¹ = 28239259 is a prime.

It is a super-2 number, since 2×28239261² = 1594911723652242, which contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28239271) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 173166 + ... + 173328.

It is an arithmetic number, because the mean of its divisors is an integer number (1298880).

Almost surely, 2^28239261 is an apocalyptic number.

It is an amenable number.

28239261 is a deficient number, since it is larger than the sum of its proper divisors (13324899).

28239261 is a wasteful number, since it uses less digits than its factorization.

28239261 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 305.

The product of its digits is 10368, while the sum is 33.

The square root of 28239261 is about 5314.0625701999. The cubic root of 28239261 is about 304.5213705844.

The spelling of 28239261 in words is "twenty-eight million, two hundred thirty-nine thousand, two hundred sixty-one".