18218729 has 2 divisors, whose sum is σ = 18218730. Its totient is φ = 18218728.

The previous prime is 18218723. The next prime is 18218771. The reversal of 18218729 is 92781281.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14077504 + 4141225 = 3752^2 + 2035^2 .

It is an emirp because it is prime and its reverse (92781281) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18218729 - 2¹⁶ = 18153193 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 18218692 and 18218701.

It is not a weakly prime, because it can be changed into another prime (18218723) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9109364 + 9109365.

It is an arithmetic number, because the mean of its divisors is an integer number (9109365).

Almost surely, 2^18218729 is an apocalyptic number.

It is an amenable number.

18218729 is a deficient number, since it is larger than the sum of its proper divisors (1).

18218729 is an equidigital number, since it uses as much as digits as its factorization.

18218729 is an evil number, because the sum of its binary digits is even.

The product of its digits is 16128, while the sum is 38.

The square root of 18218729 is about 4268.3403097691. The cubic root of 18218729 is about 263.1314094124.

The spelling of 18218729 in words is "eighteen million, two hundred eighteen thousand, seven hundred twenty-nine".