81639141 has 16 divisors (see below), whose sum is σ = 111504384. Its totient is φ = 53107184.

The previous prime is 81639109. The next prime is 81639157. The reversal of 81639141 is 14193618.

It is a cyclic number.

It is not a de Polignac number, because 81639141 - 2⁵ = 81639109 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81639191) 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 15 ways as a sum of consecutive naturals, for example, 61810 + ... + 63116.

It is an arithmetic number, because the mean of its divisors is an integer number (6969024).

Almost surely, 2^81639141 is an apocalyptic number.

It is an amenable number.

81639141 is a deficient number, since it is larger than the sum of its proper divisors (29865243).

81639141 is a wasteful number, since it uses less digits than its factorization.

81639141 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1800.

The product of its digits is 5184, while the sum is 33.

The square root of 81639141 is about 9035.4380635363. The cubic root of 81639141 is about 433.8099166178.

The spelling of 81639141 in words is "eighty-one million, six hundred thirty-nine thousand, one hundred forty-one".