81330399 has 12 divisors (see below), whose sum is σ = 121828616. Its totient is φ = 54220104.

The previous prime is 81330377. The next prime is 81330401. The reversal of 81330399 is 99303318.

It is not a de Polignac number, because 81330399 - 2¹⁹ = 80806111 is a prime.

It is a super-2 number, since 2×81330399² = 13229267602998402, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81330299) 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 in 11 ways as a sum of consecutive naturals, for example, 167104 + ... + 167589.

Almost surely, 2^81330399 is an apocalyptic number.

81330399 is a deficient number, since it is larger than the sum of its proper divisors (40498217).

81330399 is an equidigital number, since it uses as much as digits as its factorization.

81330399 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 334708 (or 334696 counting only the distinct ones).

The product of its (nonzero) digits is 17496, while the sum is 36.

The square root of 81330399 is about 9018.3368200572. The cubic root of 81330399 is about 433.2623666165.

The spelling of 81330399 in words is "eighty-one million, three hundred thirty thousand, three hundred ninety-nine".