18018661 has 2 divisors, whose sum is σ = 18018662. Its totient is φ = 18018660.

The previous prime is 18018629. The next prime is 18018697. The reversal of 18018661 is 16681081.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17589636 + 429025 = 4194^2 + 655^2 .

It is an emirp because it is prime and its reverse (16681081) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18018661 - 2⁵ = 18018629 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18018601) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9009330 + 9009331.

It is an arithmetic number, because the mean of its divisors is an integer number (9009331).

Almost surely, 2^18018661 is an apocalyptic number.

It is an amenable number.

18018661 is a deficient number, since it is larger than the sum of its proper divisors (1).

18018661 is an equidigital number, since it uses as much as digits as its factorization.

18018661 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2304, while the sum is 31.

The square root of 18018661 is about 4244.8393373601. The cubic root of 18018661 is about 262.1646741697.

The spelling of 18018661 in words is "eighteen million, eighteen thousand, six hundred sixty-one".