81890071 has 8 divisors (see below), whose sum is σ = 86793120. Its totient is φ = 76996608.

The previous prime is 81890063. The next prime is 81890077. The reversal of 81890071 is 17009818.

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 81890071 - 2³ = 81890063 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 (81890077) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 22935 + ... + 26263.

It is an arithmetic number, because the mean of its divisors is an integer number (10849140).

Almost surely, 2^81890071 is an apocalyptic number.

81890071 is a deficient number, since it is larger than the sum of its proper divisors (4903049).

81890071 is a wasteful number, since it uses less digits than its factorization.

81890071 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4793.

The product of its (nonzero) digits is 4032, while the sum is 34.

The square root of 81890071 is about 9049.3132888634. The cubic root of 81890071 is about 434.2539217149.

Adding to 81890071 its reverse (17009818), we get a palindrome (98899889).

The spelling of 81890071 in words is "eighty-one million, eight hundred ninety thousand, seventy-one".