81938159 has 4 divisors (see below), whose sum is σ = 83484216. Its totient is φ = 80392104.

The previous prime is 81938141. The next prime is 81938173. The reversal of 81938159 is 95183918.

It is a happy number.

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 81938159 - 2⁸ = 81937903 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81938179) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 772949 + ... + 773054.

It is an arithmetic number, because the mean of its divisors is an integer number (20871054).

Almost surely, 2^81938159 is an apocalyptic number.

81938159 is a deficient number, since it is larger than the sum of its proper divisors (1546057).

81938159 is a wasteful number, since it uses less digits than its factorization.

81938159 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1546056.

The product of its digits is 77760, while the sum is 44.

The square root of 81938159 is about 9051.9698961055. The cubic root of 81938159 is about 434.3389068504.

The spelling of 81938159 in words is "eighty-one million, nine hundred thirty-eight thousand, one hundred fifty-nine".