81818881 has 4 divisors (see below), whose sum is σ = 81923632. Its totient is φ = 81714132.

The previous prime is 81818879. The next prime is 81818887. The reversal of 81818881 is 18881818.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 81818881 - 2¹ = 81818879 is a prime.

It is a super-2 number, since 2×81818881² = 13388658576184322, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81818887) 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, 51195 + ... + 52768.

It is an arithmetic number, because the mean of its divisors is an integer number (20480908).

Almost surely, 2^81818881 is an apocalyptic number.

It is an amenable number.

81818881 is a deficient number, since it is larger than the sum of its proper divisors (104751).

81818881 is a wasteful number, since it uses less digits than its factorization.

81818881 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 104750.

The product of its digits is 32768, while the sum is 43.

The square root of 81818881 is about 9045.3789859795. The cubic root of 81818881 is about 434.1280476864.

The spelling of 81818881 in words is "eighty-one million, eight hundred eighteen thousand, eight hundred eighty-one".