28782181 has 8 divisors (see below), whose sum is σ = 29979000. Its totient is φ = 27599040.

The previous prime is 28782133. The next prime is 28782197. The reversal of 28782181 is 18128782.

It can be written as a sum of positive squares in 4 ways, for example, as 5597956 + 23184225 = 2366^2 + 4815^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 28782181 - 2¹⁷ = 28651109 is a prime.

It is a super-2 number, since 2×28782181² = 1656827886233522, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 28782181.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28782101) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 991 + ... + 7651.

It is an arithmetic number, because the mean of its divisors is an integer number (3747375).

Almost surely, 2^28782181 is an apocalyptic number.

It is an amenable number.

28782181 is a deficient number, since it is larger than the sum of its proper divisors (1196819).

28782181 is a wasteful number, since it uses less digits than its factorization.

28782181 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6839.

The product of its digits is 14336, while the sum is 37.

The square root of 28782181 is about 5364.9027018204. The cubic root of 28782181 is about 306.4605429347.

The spelling of 28782181 in words is "twenty-eight million, seven hundred eighty-two thousand, one hundred eighty-one".