81659139 has 8 divisors (see below), whose sum is σ = 109600512. Its totient is φ = 54078600.

The previous prime is 81659129. The next prime is 81659147. The reversal of 81659139 is 93195618.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 81659139 - 2⁹ = 81658627 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81659139.

It is not an unprimeable number, because it can be changed into a prime (81659119) 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 in 7 ways as a sum of consecutive naturals, for example, 89679 + ... + 90584.

It is an arithmetic number, because the mean of its divisors is an integer number (13700064).

Almost surely, 2^81659139 is an apocalyptic number.

81659139 is a deficient number, since it is larger than the sum of its proper divisors (27941373).

81659139 is a wasteful number, since it uses less digits than its factorization.

81659139 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 180417.

The product of its digits is 58320, while the sum is 42.

The square root of 81659139 is about 9036.5446383006. The cubic root of 81659139 is about 433.8453351779.

The spelling of 81659139 in words is "eighty-one million, six hundred fifty-nine thousand, one hundred thirty-nine".