66818 has 4 divisors (see below), whose sum is σ = 100230. Its totient is φ = 33408.

The previous prime is 66809. The next prime is 66821. The reversal of 66818 is 81866.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 81866 = 2 ⋅40933.

It can be written as a sum of positive squares in only one way, i.e., 64009 + 2809 = 253^2 + 53^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 16703 + ... + 16706.

2⁶⁶⁸¹⁸ is an apocalyptic number.

66818 is a deficient number, since it is larger than the sum of its proper divisors (33412).

66818 is a wasteful number, since it uses less digits than its factorization.

66818 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33411.

The product of its digits is 2304, while the sum is 29.

The square root of 66818 is about 258.4917793664. The cubic root of 66818 is about 40.5786714476.

It can be divided in two parts, 668 and 18, that added together give a palindrome (686).

The spelling of 66818 in words is "sixty-six thousand, eight hundred eighteen".