28102181 has 2 divisors, whose sum is σ = 28102182. Its totient is φ = 28102180.

The previous prime is 28102169. The next prime is 28102201. The reversal of 28102181 is 18120182.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 24661156 + 3441025 = 4966^2 + 1855^2 .

It is a cyclic number.

It is not a de Polignac number, because 28102181 - 2¹⁸ = 27840037 is a prime.

It is a super-4 number, since 4×28102181⁴ (a number of 31 digits) contains 4444 as substring. Note that it is a super-d number also for d = 2.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (28152181) by changing a digit.

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, 14051090 + 14051091.

It is an arithmetic number, because the mean of its divisors is an integer number (14051091).

Almost surely, 2^28102181 is an apocalyptic number.

It is an amenable number.

28102181 is a deficient number, since it is larger than the sum of its proper divisors (1).

28102181 is an equidigital number, since it uses as much as digits as its factorization.

28102181 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 256, while the sum is 23.

The square root of 28102181 is about 5301.1490263904. The cubic root of 28102181 is about 304.0278317374.

The spelling of 28102181 in words is "twenty-eight million, one hundred two thousand, one hundred eighty-one".