28172489 has 4 divisors (see below), whose sum is σ = 28213380. Its totient is φ = 28131600.

The previous prime is 28172479. The next prime is 28172513. The reversal of 28172489 is 98427182.

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 10465225 + 17707264 = 3235^2 + 4208^2 .

It is a cyclic number.

It is not a de Polignac number, because 28172489 - 2²⁰ = 27123913 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (28172449) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 19394 + ... + 20795.

It is an arithmetic number, because the mean of its divisors is an integer number (7053345).

Almost surely, 2^28172489 is an apocalyptic number.

It is an amenable number.

28172489 is a deficient number, since it is larger than the sum of its proper divisors (40891).

28172489 is an equidigital number, since it uses as much as digits as its factorization.

28172489 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40890.

The product of its digits is 64512, while the sum is 41.

The square root of 28172489 is about 5307.7762763704. The cubic root of 28172489 is about 304.2811666087.

The spelling of 28172489 in words is "twenty-eight million, one hundred seventy-two thousand, four hundred eighty-nine".