18618557 has 2 divisors, whose sum is σ = 18618558. Its totient is φ = 18618556.

The previous prime is 18618541. The next prime is 18618583. The reversal of 18618557 is 75581681.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18567481 + 51076 = 4309^2 + 226^2 .

It is a cyclic number.

It is not a de Polignac number, because 18618557 - 2⁴ = 18618541 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 (18618857) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9309278 + 9309279.

It is an arithmetic number, because the mean of its divisors is an integer number (9309279).

Almost surely, 2^18618557 is an apocalyptic number.

It is an amenable number.

18618557 is a deficient number, since it is larger than the sum of its proper divisors (1).

18618557 is an equidigital number, since it uses as much as digits as its factorization.

18618557 is an evil number, because the sum of its binary digits is even.

The product of its digits is 67200, while the sum is 41.

The square root of 18618557 is about 4314.9225949025. The cubic root of 18618557 is about 265.0423902758.

The spelling of 18618557 in words is "eighteen million, six hundred eighteen thousand, five hundred fifty-seven".