81065939 has 4 divisors (see below), whose sum is σ = 81490560. Its totient is φ = 80641320.

The previous prime is 81065903. The next prime is 81065987. The reversal of 81065939 is 93956018.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 81065939 - 2⁸ = 81065683 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 81065896 and 81065905.

It is not an unprimeable number, because it can be changed into a prime (81065239) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 212024 + ... + 212405.

It is an arithmetic number, because the mean of its divisors is an integer number (20372640).

Almost surely, 2^81065939 is an apocalyptic number.

81065939 is a deficient number, since it is larger than the sum of its proper divisors (424621).

81065939 is a wasteful number, since it uses less digits than its factorization.

81065939 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 424620.

The product of its (nonzero) digits is 58320, while the sum is 41.

The square root of 81065939 is about 9003.6625325475. The cubic root of 81065939 is about 432.7922472653.

The spelling of 81065939 in words is "eighty-one million, sixty-five thousand, nine hundred thirty-nine".