211818 has 16 divisors (see below), whose sum is σ = 434016. Its totient is φ = 68880.

The previous prime is 211817. The next prime is 211859. The reversal of 211818 is 818112.

It is a junction number, because it is equal to n+sod(n) for n = 211794 and 211803.

It is not an unprimeable number, because it can be changed into a prime (211811) 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, 153 + ... + 668.

It is an arithmetic number, because the mean of its divisors is an integer number (27126).

2²¹¹⁸¹⁸ is an apocalyptic number.

211818 is an abundant number, since it is smaller than the sum of its proper divisors (222198).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

211818 is a wasteful number, since it uses less digits than its factorization.

211818 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 869.

The product of its digits is 128, while the sum is 21.

The square root of 211818 is about 460.2368955223. The cubic root of 211818 is about 59.6102515285.

The spelling of 211818 in words is "two hundred eleven thousand, eight hundred eighteen".