28564691 has 4 divisors (see below), whose sum is σ = 28619832. Its totient is φ = 28509552.

The previous prime is 28564687. The next prime is 28564717. The reversal of 28564691 is 19646582.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 19646582 = 2 ⋅9823291.

It is a cyclic number.

It is not a de Polignac number, because 28564691 - 2² = 28564687 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28564621) 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, 26786 + ... + 27831.

It is an arithmetic number, because the mean of its divisors is an integer number (7154958).

Almost surely, 2^28564691 is an apocalyptic number.

28564691 is a deficient number, since it is larger than the sum of its proper divisors (55141).

28564691 is an equidigital number, since it uses as much as digits as its factorization.

28564691 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 55140.

The product of its digits is 103680, while the sum is 41.

The square root of 28564691 is about 5344.5945589914. The cubic root of 28564691 is about 305.6866764535.

The spelling of 28564691 in words is "twenty-eight million, five hundred sixty-four thousand, six hundred ninety-one".