28399997 has 4 divisors (see below), whose sum is σ = 28935900. Its totient is φ = 27864096.

The previous prime is 28399991. The next prime is 28400011. The reversal of 28399997 is 79999382.

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

It can be written as a sum of positive squares in 2 ways, for example, as 26152996 + 2247001 = 5114^2 + 1499^2 .

It is a cyclic number.

It is not a de Polignac number, because 28399997 - 2⁶ = 28399933 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 (28399991) 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, 267872 + ... + 267977.

It is an arithmetic number, because the mean of its divisors is an integer number (7233975).

Almost surely, 2^28399997 is an apocalyptic number.

It is an amenable number.

28399997 is a deficient number, since it is larger than the sum of its proper divisors (535903).

28399997 is an equidigital number, since it uses as much as digits as its factorization.

28399997 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 535902.

The product of its digits is 2204496, while the sum is 56.

The square root of 28399997 is about 5329.1647563197. The cubic root of 28399997 is about 305.0980496372.

The spelling of 28399997 in words is "twenty-eight million, three hundred ninety-nine thousand, nine hundred ninety-seven".