667818 has 32 divisors (see below), whose sum is σ = 1512000. Its totient is φ = 218448.

The previous prime is 667817. The next prime is 667819. The reversal of 667818 is 818766.

It is an interprime number because it is at equal distance from previous prime (667817) and next prime (667819).

It is a super-2 number, since 2×667818² = 891961762248, which contains 22 as substring.

It is a Smith number, since the sum of its digits (36) coincides with the sum of the digits of its prime factors.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (667817) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4408 + ... + 4556.

It is an arithmetic number, because the mean of its divisors is an integer number (47250).

2⁶⁶⁷⁸¹⁸ is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 667818, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (756000).

667818 is an abundant number, since it is smaller than the sum of its proper divisors (844182).

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

667818 is a wasteful number, since it uses less digits than its factorization.

667818 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 243 (or 237 counting only the distinct ones).

The product of its digits is 16128, while the sum is 36.

The square root of 667818 is about 817.2013215848. The cubic root of 667818 is about 87.4083066670.

It can be divided in two parts, 667 and 818, that added together give a triangular number (1485 = T₅₄).

The spelling of 667818 in words is "six hundred sixty-seven thousand, eight hundred eighteen".