18705257 has 2 divisors, whose sum is σ = 18705258. Its totient is φ = 18705256.

The previous prime is 18705227. The next prime is 18705259. The reversal of 18705257 is 75250781.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18696976 + 8281 = 4324^2 + 91^2 .

It is a cyclic number.

It is not a de Polignac number, because 18705257 - 2²⁴ = 1928041 is a prime.

Together with 18705259, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (18705259) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9352628 + 9352629.

It is an arithmetic number, because the mean of its divisors is an integer number (9352629).

Almost surely, 2^18705257 is an apocalyptic number.

It is an amenable number.

18705257 is a deficient number, since it is larger than the sum of its proper divisors (1).

18705257 is an equidigital number, since it uses as much as digits as its factorization.

18705257 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 19600, while the sum is 35.

The square root of 18705257 is about 4324.9574564382. The cubic root of 18705257 is about 265.4531560620.

The spelling of 18705257 in words is "eighteen million, seven hundred five thousand, two hundred fifty-seven".