28660391 has 4 divisors (see below), whose sum is σ = 28826232. Its totient is φ = 28494552.

The previous prime is 28660367. The next prime is 28660393. The reversal of 28660391 is 19306682.

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 28660391 - 2⁶ = 28660327 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28660393) 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, 82661 + ... + 83006.

It is an arithmetic number, because the mean of its divisors is an integer number (7206558).

Almost surely, 2^28660391 is an apocalyptic number.

28660391 is a deficient number, since it is larger than the sum of its proper divisors (165841).

28660391 is a wasteful number, since it uses less digits than its factorization.

28660391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 165840.

The product of its (nonzero) digits is 15552, while the sum is 35.

The square root of 28660391 is about 5353.5400437468. The cubic root of 28660391 is about 306.0276755979.

The spelling of 28660391 in words is "twenty-eight million, six hundred sixty thousand, three hundred ninety-one".