28171831 has 4 divisors (see below), whose sum is σ = 28192600. Its totient is φ = 28151064.

The previous prime is 28171823. The next prime is 28171841. The reversal of 28171831 is 13817182.

It is a happy number.

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 28171831 - 2³ = 28171823 is a prime.

It is a super-2 number, since 2×28171831² = 1587304123785122, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 28171793 and 28171802.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28171841) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8196 + ... + 11113.

It is an arithmetic number, because the mean of its divisors is an integer number (7048150).

Almost surely, 2^28171831 is an apocalyptic number.

28171831 is a deficient number, since it is larger than the sum of its proper divisors (20769).

28171831 is a wasteful number, since it uses less digits than its factorization.

28171831 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20768.

The product of its digits is 2688, while the sum is 31.

The square root of 28171831 is about 5307.7142914818. The cubic root of 28171831 is about 304.2787976479.

The spelling of 28171831 in words is "twenty-eight million, one hundred seventy-one thousand, eight hundred thirty-one".