28239691 has 4 divisors (see below), whose sum is σ = 28896472. Its totient is φ = 27582912.

The previous prime is 28239689. The next prime is 28239697. The reversal of 28239691 is 19693282.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 28239691 - 2¹ = 28239689 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28239697) 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, 328326 + ... + 328411.

It is an arithmetic number, because the mean of its divisors is an integer number (7224118).

Almost surely, 2^28239691 is an apocalyptic number.

28239691 is a deficient number, since it is larger than the sum of its proper divisors (656781).

28239691 is an equidigital number, since it uses as much as digits as its factorization.

28239691 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 656780.

The product of its digits is 46656, while the sum is 40.

The square root of 28239691 is about 5314.1030287340. The cubic root of 28239691 is about 304.5229162283.

The spelling of 28239691 in words is "twenty-eight million, two hundred thirty-nine thousand, six hundred ninety-one".