28381018 has 4 divisors (see below), whose sum is σ = 42571530. Its totient is φ = 14190508.

The previous prime is 28381009. The next prime is 28381021. The reversal of 28381018 is 81018382.

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

It can be written as a sum of positive squares in only one way, i.e., 19035769 + 9345249 = 4363^2 + 3057^2 .

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 an unprimeable number.

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 as a sum of consecutive naturals, namely, 7095253 + ... + 7095256.

Almost surely, 2^28381018 is an apocalyptic number.

28381018 is a deficient number, since it is larger than the sum of its proper divisors (14190512).

28381018 is a wasteful number, since it uses less digits than its factorization.

28381018 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14190511.

The product of its (nonzero) digits is 3072, while the sum is 31.

The square root of 28381018 is about 5327.3837856869. The cubic root of 28381018 is about 305.0300713878.

The spelling of 28381018 in words is "twenty-eight million, three hundred eighty-one thousand, eighteen".