81326191 has 2 divisors, whose sum is σ = 81326192. Its totient is φ = 81326190.

The previous prime is 81326171. The next prime is 81326209. The reversal of 81326191 is 19162318.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81326191 - 2⁵ = 81326159 is a prime.

It is a super-2 number, since 2×81326191² = 13227898685136962, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81326171) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40663095 + 40663096.

It is an arithmetic number, because the mean of its divisors is an integer number (40663096).

Almost surely, 2^81326191 is an apocalyptic number.

81326191 is a deficient number, since it is larger than the sum of its proper divisors (1).

81326191 is an equidigital number, since it uses as much as digits as its factorization.

81326191 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2592, while the sum is 31.

The square root of 81326191 is about 9018.1035145977. The cubic root of 81326191 is about 433.2548942178.

The spelling of 81326191 in words is "eighty-one million, three hundred twenty-six thousand, one hundred ninety-one".