161818 has 4 divisors (see below), whose sum is σ = 242730. Its totient is φ = 80908.

The previous prime is 161807. The next prime is 161831. The reversal of 161818 is 818161.

It is a happy number.

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., 146689 + 15129 = 383^2 + 123^2 .

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

161818 is a modest number, since divided by 1818 gives 16 as remainder.

It is a junction number, because it is equal to n+sod(n) for n = 161792 and 161801.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40453 + ... + 40456.

2¹⁶¹⁸¹⁸ is an apocalyptic number.

161818 is a deficient number, since it is larger than the sum of its proper divisors (80912).

161818 is an equidigital number, since it uses as much as digits as its factorization.

161818 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 80911.

The product of its digits is 384, while the sum is 25.

The square root of 161818 is about 402.2660810956. The cubic root of 161818 is about 54.4931955705.

Adding to 161818 its reverse (818161), we get a palindrome (979979).

It can be divided in two parts, 161 and 818, that added together give a palindrome (979).

The spelling of 161818 in words is "one hundred sixty-one thousand, eight hundred eighteen".