81818161 has 8 divisors (see below), whose sum is σ = 91190880. Its totient is φ = 72952128.

The previous prime is 81818147. The next prime is 81818173. The reversal of 81818161 is 16181818.

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 81818161 - 2⁵ = 81818129 is a prime.

It is a super-2 number, since 2×81818161² = 13388422938843842, which contains 22 as substring.

It is an alternating number because its digits alternate between even and odd.

It is not an unprimeable number, because it can be changed into a prime (81818111) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 126331 + ... + 126976.

It is an arithmetic number, because the mean of its divisors is an integer number (11398860).

Almost surely, 2^81818161 is an apocalyptic number.

It is an amenable number.

81818161 is a deficient number, since it is larger than the sum of its proper divisors (9372719).

81818161 is a wasteful number, since it uses less digits than its factorization.

81818161 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 253343.

The product of its digits is 3072, while the sum is 34.

The square root of 81818161 is about 9045.3391865645. The cubic root of 81818161 is about 434.1267742512.

Adding to 81818161 its reverse (16181818), we get a palindrome (97999979).

The spelling of 81818161 in words is "eighty-one million, eight hundred eighteen thousand, one hundred sixty-one".