81184189 has 2 divisors, whose sum is σ = 81184190. Its totient is φ = 81184188.

The previous prime is 81184171. The next prime is 81184199. The reversal of 81184189 is 98148118.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 79032100 + 2152089 = 8890^2 + 1467^2 .

It is a cyclic number.

It is not a de Polignac number, because 81184189 - 2²¹ = 79087037 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81184199) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40592094 + 40592095.

It is an arithmetic number, because the mean of its divisors is an integer number (40592095).

Almost surely, 2^81184189 is an apocalyptic number.

It is an amenable number.

81184189 is a deficient number, since it is larger than the sum of its proper divisors (1).

81184189 is an equidigital number, since it uses as much as digits as its factorization.

81184189 is an evil number, because the sum of its binary digits is even.

The product of its digits is 18432, while the sum is 40.

The square root of 81184189 is about 9010.2269116821. The cubic root of 81184189 is about 433.0025814694.

The spelling of 81184189 in words is "eighty-one million, one hundred eighty-four thousand, one hundred eighty-nine".