81384109 has 2 divisors, whose sum is σ = 81384110. Its totient is φ = 81384108.

The previous prime is 81384101. The next prime is 81384131. The reversal of 81384109 is 90148318.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 69973225 + 11410884 = 8365^2 + 3378^2 .

It is a cyclic number.

It is not a de Polignac number, because 81384109 - 2³ = 81384101 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81384101) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40692054 + 40692055.

It is an arithmetic number, because the mean of its divisors is an integer number (40692055).

Almost surely, 2^81384109 is an apocalyptic number.

It is an amenable number.

81384109 is a deficient number, since it is larger than the sum of its proper divisors (1).

81384109 is an equidigital number, since it uses as much as digits as its factorization.

81384109 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 6912, while the sum is 34.

The square root of 81384109 is about 9021.3141503885. The cubic root of 81384109 is about 433.3577200608.

The spelling of 81384109 in words is "eighty-one million, three hundred eighty-four thousand, one hundred nine".