81199397 has 2 divisors, whose sum is σ = 81199398. Its totient is φ = 81199396.

The previous prime is 81199367. The next prime is 81199403. The reversal of 81199397 is 79399118.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 49547521 + 31651876 = 7039^2 + 5626^2 .

It is a cyclic number.

It is not a de Polignac number, because 81199397 - 2¹⁰ = 81198373 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81199337) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40599698 + 40599699.

It is an arithmetic number, because the mean of its divisors is an integer number (40599699).

Almost surely, 2^81199397 is an apocalyptic number.

It is an amenable number.

81199397 is a deficient number, since it is larger than the sum of its proper divisors (1).

81199397 is an equidigital number, since it uses as much as digits as its factorization.

81199397 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 122472, while the sum is 47.

The square root of 81199397 is about 9011.0708020745. The cubic root of 81199397 is about 433.0296174896.

The spelling of 81199397 in words is "eighty-one million, one hundred ninety-nine thousand, three hundred ninety-seven".