81288191 has 2 divisors, whose sum is σ = 81288192. Its totient is φ = 81288190.

The previous prime is 81288161. The next prime is 81288197. The reversal of 81288191 is 19188218.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81288191 - 2¹⁴ = 81271807 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81288197) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40644095 + 40644096.

It is an arithmetic number, because the mean of its divisors is an integer number (40644096).

Almost surely, 2^81288191 is an apocalyptic number.

81288191 is a deficient number, since it is larger than the sum of its proper divisors (1).

81288191 is an equidigital number, since it uses as much as digits as its factorization.

81288191 is an evil number, because the sum of its binary digits is even.

The product of its digits is 9216, while the sum is 38.

The square root of 81288191 is about 9015.9963952965. The cubic root of 81288191 is about 433.1874036563.

The spelling of 81288191 in words is "eighty-one million, two hundred eighty-eight thousand, one hundred ninety-one".