28340391 has 4 divisors (see below), whose sum is σ = 37787192. Its totient is φ = 18893592.

The previous prime is 28340387. The next prime is 28340399. The reversal of 28340391 is 19304382.

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

It is not a de Polignac number, because 28340391 - 2² = 28340387 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 (28340399) 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, 4723396 + ... + 4723401.

It is an arithmetic number, because the mean of its divisors is an integer number (9446798).

Almost surely, 2^28340391 is an apocalyptic number.

28340391 is a deficient number, since it is larger than the sum of its proper divisors (9446801).

28340391 is an equidigital number, since it uses as much as digits as its factorization.

28340391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9446800.

The product of its (nonzero) digits is 5184, while the sum is 30.

The square root of 28340391 is about 5323.5693852903. The cubic root of 28340391 is about 304.8844532306.

The spelling of 28340391 in words is "twenty-eight million, three hundred forty thousand, three hundred ninety-one".