28870391 has 4 divisors (see below), whose sum is σ = 31494984. Its totient is φ = 26245800.

The previous prime is 28870379. The next prime is 28870409. The reversal of 28870391 is 19307882.

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 28870391 - 2¹⁰ = 28869367 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 (28870321) 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, 1312280 + ... + 1312301.

It is an arithmetic number, because the mean of its divisors is an integer number (7873746).

Almost surely, 2^28870391 is an apocalyptic number.

28870391 is a deficient number, since it is larger than the sum of its proper divisors (2624593).

28870391 is a wasteful number, since it uses less digits than its factorization.

28870391 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2624592.

The product of its (nonzero) digits is 24192, while the sum is 38.

The square root of 28870391 is about 5373.1174377637. The cubic root of 28870391 is about 306.7732979588.

The spelling of 28870391 in words is "twenty-eight million, eight hundred seventy thousand, three hundred ninety-one".