18143666 has 4 divisors (see below), whose sum is σ = 27215502. Its totient is φ = 9071832.

The previous prime is 18143659. The next prime is 18143681. The reversal of 18143666 is 66634181.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 66634181 = 73 ⋅912797.

It can be written as a sum of positive squares in only one way, i.e., 10465225 + 7678441 = 3235^2 + 2771^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4535915 + ... + 4535918.

Almost surely, 2^18143666 is an apocalyptic number.

18143666 is a deficient number, since it is larger than the sum of its proper divisors (9071836).

18143666 is an equidigital number, since it uses as much as digits as its factorization.

18143666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9071835.

The product of its digits is 20736, while the sum is 35.

The square root of 18143666 is about 4259.5382378845. The cubic root of 18143666 is about 262.7695359943.

The spelling of 18143666 in words is "eighteen million, one hundred forty-three thousand, six hundred sixty-six".