81393871 has 8 divisors (see below), whose sum is σ = 87935904. Its totient is φ = 74892000.

The previous prime is 81393869. The next prime is 81393889. The reversal of 81393871 is 17839318.

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

It is a cyclic number.

It is not a de Polignac number, because 81393871 - 2¹ = 81393869 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 (81393371) 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 7 ways as a sum of consecutive naturals, for example, 5755 + ... + 13996.

It is an arithmetic number, because the mean of its divisors is an integer number (10991988).

Almost surely, 2^81393871 is an apocalyptic number.

81393871 is a deficient number, since it is larger than the sum of its proper divisors (6542033).

81393871 is a wasteful number, since it uses less digits than its factorization.

81393871 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20081.

The product of its digits is 36288, while the sum is 40.

The square root of 81393871 is about 9021.8551861577. The cubic root of 81393871 is about 433.3750464119.

The spelling of 81393871 in words is "eighty-one million, three hundred ninety-three thousand, eight hundred seventy-one".