81218 has 4 divisors (see below), whose sum is σ = 121830. Its totient is φ = 40608.

The previous prime is 81203. The next prime is 81223.

81218 is nontrivially palindromic in base 10.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 76729 + 4489 = 277^2 + 67^2 .

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

It is a self number, because there is not a number n which added to its sum of digits gives 81218.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20303 + ... + 20306.

2⁸¹²¹⁸ is an apocalyptic number.

81218 is a deficient number, since it is larger than the sum of its proper divisors (40612).

81218 is a wasteful number, since it uses less digits than its factorization.

81218 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40611.

The product of its digits is 128, while the sum is 20.

The square root of 81218 is about 284.9877190336. The cubic root of 81218 is about 43.3062684381.

The spelling of 81218 in words is "eighty-one thousand, two hundred eighteen".