81133399 has 2 divisors, whose sum is σ = 81133400. Its totient is φ = 81133398.

The previous prime is 81133391. The next prime is 81133427. The reversal of 81133399 is 99333118.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81133399 - 2³ = 81133391 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81133391) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40566699 + 40566700.

It is an arithmetic number, because the mean of its divisors is an integer number (40566700).

Almost surely, 2^81133399 is an apocalyptic number.

81133399 is a deficient number, since it is larger than the sum of its proper divisors (1).

81133399 is an equidigital number, since it uses as much as digits as its factorization.

81133399 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 17496, while the sum is 37.

The square root of 81133399 is about 9007.4080067464. The cubic root of 81133399 is about 432.9122650782.

The spelling of 81133399 in words is "eighty-one million, one hundred thirty-three thousand, three hundred ninety-nine".