28155181 has 2 divisors, whose sum is σ = 28155182. Its totient is φ = 28155180.

The previous prime is 28155173. The next prime is 28155199. The reversal of 28155181 is 18155182.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 27405225 + 749956 = 5235^2 + 866^2 .

It is a cyclic number.

It is not a de Polignac number, because 28155181 - 2³ = 28155173 is a prime.

It is a super-2 number, since 2×28155181² = 1585428434285522, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (28155481) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14077590 + 14077591.

It is an arithmetic number, because the mean of its divisors is an integer number (14077591).

Almost surely, 2^28155181 is an apocalyptic number.

It is an amenable number.

28155181 is a deficient number, since it is larger than the sum of its proper divisors (1).

28155181 is an equidigital number, since it uses as much as digits as its factorization.

28155181 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3200, while the sum is 31.

The square root of 28155181 is about 5306.1455879009. The cubic root of 28155181 is about 304.2188412990.

Subtracting from 28155181 its reverse (18155182), we obtain a palindrome (9999999).

The spelling of 28155181 in words is "twenty-eight million, one hundred fifty-five thousand, one hundred eighty-one".