28158197 has 4 divisors (see below), whose sum is σ = 28198080. Its totient is φ = 28118316.

The previous prime is 28158191. The next prime is 28158257. The reversal of 28158197 is 79185182.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 28158197 - 2⁴ = 28158181 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 (28158191) 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, 18863 + ... + 20300.

It is an arithmetic number, because the mean of its divisors is an integer number (7049520).

Almost surely, 2^28158197 is an apocalyptic number.

It is an amenable number.

28158197 is a deficient number, since it is larger than the sum of its proper divisors (39883).

28158197 is an equidigital number, since it uses as much as digits as its factorization.

28158197 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 39882.

The product of its digits is 40320, while the sum is 41.

The square root of 28158197 is about 5306.4297790511. The cubic root of 28158197 is about 304.2297036132.

The spelling of 28158197 in words is "twenty-eight million, one hundred fifty-eight thousand, one hundred ninety-seven".