28047181 has 4 divisors (see below), whose sum is σ = 28156572. Its totient is φ = 27937792.

The previous prime is 28047179. The next prime is 28047197. The reversal of 28047181 is 18174082.

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 22944100 + 5103081 = 4790^2 + 2259^2 .

It is a cyclic number.

It is not a de Polignac number, because 28047181 - 2¹ = 28047179 is a prime.

It is a super-2 number, since 2×28047181² = 1573288724093522, which contains 22 as substring.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28047101) 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, 54310 + ... + 54823.

It is an arithmetic number, because the mean of its divisors is an integer number (7039143).

Almost surely, 2^28047181 is an apocalyptic number.

It is an amenable number.

28047181 is a deficient number, since it is larger than the sum of its proper divisors (109391).

28047181 is a wasteful number, since it uses less digits than its factorization.

28047181 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 109390.

The product of its (nonzero) digits is 3584, while the sum is 31.

The square root of 28047181 is about 5295.9589311096. The cubic root of 28047181 is about 303.8293601736.

The spelling of 28047181 in words is "twenty-eight million, forty-seven thousand, one hundred eighty-one".