28278181 has 2 divisors, whose sum is σ = 28278182. Its totient is φ = 28278180.

The previous prime is 28278139. The next prime is 28278199. The reversal of 28278181 is 18187282.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17715681 + 10562500 = 4209^2 + 3250^2 .

It is a cyclic number.

It is not a de Polignac number, because 28278181 - 2¹⁷ = 28147109 is a prime.

It is a super-2 number, since 2×28278181² = 1599311041337522, 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 28278181.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (28278121) 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 as a sum of consecutive naturals, namely, 14139090 + 14139091.

It is an arithmetic number, because the mean of its divisors is an integer number (14139091).

Almost surely, 2^28278181 is an apocalyptic number.

It is an amenable number.

28278181 is a deficient number, since it is larger than the sum of its proper divisors (1).

28278181 is an equidigital number, since it uses as much as digits as its factorization.

28278181 is an odious number, because the sum of its binary digits is odd.

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

The square root of 28278181 is about 5317.7232910335. The cubic root of 28278181 is about 304.6612058186.

The spelling of 28278181 in words is "twenty-eight million, two hundred seventy-eight thousand, one hundred eighty-one".