28197181 has 2 divisors, whose sum is σ = 28197182. Its totient is φ = 28197180.

The previous prime is 28197179. The next prime is 28197187. The reversal of 28197181 is 18179182.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 27994681 + 202500 = 5291^2 + 450^2 .

It is a cyclic number.

It is not a de Polignac number, because 28197181 - 2¹ = 28197179 is a prime.

It is a super-2 number, since 2×28197181² = 1590162032693522, which contains 22 as substring.

Together with 28197179, it forms a pair of twin primes.

It is a self number, because there is not a number n which added to its sum of digits gives 28197181.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (28197187) 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, 14098590 + 14098591.

It is an arithmetic number, because the mean of its divisors is an integer number (14098591).

Almost surely, 2^28197181 is an apocalyptic number.

It is an amenable number.

28197181 is a deficient number, since it is larger than the sum of its proper divisors (1).

28197181 is an equidigital number, since it uses as much as digits as its factorization.

28197181 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 8064, while the sum is 37.

The square root of 28197181 is about 5310.1017881016. The cubic root of 28197181 is about 304.3700371921.

It can be divided in two parts, 2819 and 7181, that added together give a 4-th power (10000 = 10⁴).

The spelling of 28197181 in words is "twenty-eight million, one hundred ninety-seven thousand, one hundred eighty-one".