18518261 has 2 divisors, whose sum is σ = 18518262. Its totient is φ = 18518260.

The previous prime is 18518257. The next prime is 18518299. The reversal of 18518261 is 16281581.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12117361 + 6400900 = 3481^2 + 2530^2 .

It is a cyclic number.

It is not a de Polignac number, because 18518261 - 2² = 18518257 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18518231) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9259130 + 9259131.

It is an arithmetic number, because the mean of its divisors is an integer number (9259131).

Almost surely, 2^18518261 is an apocalyptic number.

It is an amenable number.

18518261 is a deficient number, since it is larger than the sum of its proper divisors (1).

18518261 is an equidigital number, since it uses as much as digits as its factorization.

18518261 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3840, while the sum is 32.

The square root of 18518261 is about 4303.2849080673. The cubic root of 18518261 is about 264.5656156335.

The spelling of 18518261 in words is "eighteen million, five hundred eighteen thousand, two hundred sixty-one".