2181818 has 4 divisors (see below), whose sum is σ = 3272730. Its totient is φ = 1090908.

The previous prime is 2181737. The next prime is 2181833. The reversal of 2181818 is 8181812.

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., 2181529 + 289 = 1477^2 + 17^2 .

It is a super-3 number, since 3×2181818³ = 31158519633359026296, which contains 333 as substring.

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

2181818 is a modest number, since divided by 1818 gives 218 as remainder.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 545453 + ... + 545456.

2^2181818 is an apocalyptic number.

2181818 is a deficient number, since it is larger than the sum of its proper divisors (1090912).

2181818 is a wasteful number, since it uses less digits than its factorization.

2181818 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1090911.

The product of its digits is 1024, while the sum is 29.

The square root of 2181818 is about 1477.0978302062. The cubic root of 2181818 is about 129.6998598468.

The spelling of 2181818 in words is "two million, one hundred eighty-one thousand, eight hundred eighteen".