18217813 has 2 divisors, whose sum is σ = 18217814. Its totient is φ = 18217812.

The previous prime is 18217741. The next prime is 18217841. The reversal of 18217813 is 31871281.

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., 17455684 + 762129 = 4178^2 + 873^2 .

It is a cyclic number.

It is not a de Polignac number, because 18217813 - 2¹³ = 18209621 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18217873) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9108906 + 9108907.

It is an arithmetic number, because the mean of its divisors is an integer number (9108907).

Almost surely, 2^18217813 is an apocalyptic number.

It is an amenable number.

18217813 is a deficient number, since it is larger than the sum of its proper divisors (1).

18217813 is an equidigital number, since it uses as much as digits as its factorization.

18217813 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2688, while the sum is 31.

The square root of 18217813 is about 4268.2330067605. The cubic root of 18217813 is about 263.1269994375.

The spelling of 18217813 in words is "eighteen million, two hundred seventeen thousand, eight hundred thirteen".