18520717 has 2 divisors, whose sum is σ = 18520718. Its totient is φ = 18520716.

The previous prime is 18520693. The next prime is 18520729. The reversal of 18520717 is 71702581.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15634116 + 2886601 = 3954^2 + 1699^2 .

It is an emirp because it is prime and its reverse (71702581) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18520717 is a prime.

It is equal to p_1182379 and since 18520717 and 1182379 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18520787) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9260358 + 9260359.

It is an arithmetic number, because the mean of its divisors is an integer number (9260359).

Almost surely, 2^18520717 is an apocalyptic number.

It is an amenable number.

18520717 is a deficient number, since it is larger than the sum of its proper divisors (1).

18520717 is an equidigital number, since it uses as much as digits as its factorization.

18520717 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3920, while the sum is 31.

The square root of 18520717 is about 4303.5702620034. The cubic root of 18520717 is about 264.5773111959.

It can be divided in two parts, 185 and 20717, that added together give a palindrome (20902).

The spelling of 18520717 in words is "eighteen million, five hundred twenty thousand, seven hundred seventeen".