28809181 has 2 divisors, whose sum is σ = 28809182. Its totient is φ = 28809180.

The previous prime is 28809163. The next prime is 28809191. The reversal of 28809181 is 18190882.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 23328900 + 5480281 = 4830^2 + 2341^2 .

It is a cyclic number.

It is not a de Polignac number, because 28809181 - 2¹⁷ = 28678109 is a prime.

It is a super-2 number, since 2×28809181² = 1659937819781522, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 28809181.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (28809191) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14404590 + 14404591.

It is an arithmetic number, because the mean of its divisors is an integer number (14404591).

Almost surely, 2^28809181 is an apocalyptic number.

It is an amenable number.

28809181 is a deficient number, since it is larger than the sum of its proper divisors (1).

28809181 is an equidigital number, since it uses as much as digits as its factorization.

28809181 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 9216, while the sum is 37.

The square root of 28809181 is about 5367.4184670100. The cubic root of 28809181 is about 306.5563411955.

The spelling of 28809181 in words is "twenty-eight million, eight hundred nine thousand, one hundred eighty-one".