18666541 has 2 divisors, whose sum is σ = 18666542. Its totient is φ = 18666540.

The previous prime is 18666533. The next prime is 18666563. The reversal of 18666541 is 14566681.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18096516 + 570025 = 4254^2 + 755^2 .

It is a cyclic number.

It is not a de Polignac number, because 18666541 - 2³ = 18666533 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 18666541.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18666511) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9333270 + 9333271.

It is an arithmetic number, because the mean of its divisors is an integer number (9333271).

Almost surely, 2^18666541 is an apocalyptic number.

It is an amenable number.

18666541 is a deficient number, since it is larger than the sum of its proper divisors (1).

18666541 is an equidigital number, since it uses as much as digits as its factorization.

18666541 is an evil number, because the sum of its binary digits is even.

The product of its digits is 34560, while the sum is 37.

The square root of 18666541 is about 4320.4792558234. The cubic root of 18666541 is about 265.2698852455.

The spelling of 18666541 in words is "eighteen million, six hundred sixty-six thousand, five hundred forty-one".