81818071 has 4 divisors (see below), whose sum is σ = 81838944. Its totient is φ = 81797200.

The previous prime is 81818069. The next prime is 81818111. The reversal of 81818071 is 17081818.

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 81818071 - 2¹ = 81818069 is a prime.

It is a super-2 number, since 2×81818071² = 13388393484322082, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81818371) 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, 2590 + ... + 13051.

It is an arithmetic number, because the mean of its divisors is an integer number (20459736).

Almost surely, 2^81818071 is an apocalyptic number.

81818071 is a deficient number, since it is larger than the sum of its proper divisors (20873).

81818071 is a wasteful number, since it uses less digits than its factorization.

81818071 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20872.

The product of its (nonzero) digits is 3584, while the sum is 34.

The square root of 81818071 is about 9045.3342116254. The cubic root of 81818071 is about 434.1266150713.

Adding to 81818071 its reverse (17081818), we get a palindrome (98899889).

The spelling of 81818071 in words is "eighty-one million, eight hundred eighteen thousand, seventy-one".