18263521 has 2 divisors, whose sum is σ = 18263522. Its totient is φ = 18263520.

The previous prime is 18263471. The next prime is 18263551. The reversal of 18263521 is 12536281.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16120225 + 2143296 = 4015^2 + 1464^2 .

It is an emirp because it is prime and its reverse (12536281) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18263521 - 2⁷ = 18263393 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 18263521.

It is not a weakly prime, because it can be changed into another prime (18263551) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9131760 + 9131761.

It is an arithmetic number, because the mean of its divisors is an integer number (9131761).

Almost surely, 2^18263521 is an apocalyptic number.

It is an amenable number.

18263521 is a deficient number, since it is larger than the sum of its proper divisors (1).

18263521 is an equidigital number, since it uses as much as digits as its factorization.

18263521 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2880, while the sum is 28.

The square root of 18263521 is about 4273.5840930067. The cubic root of 18263521 is about 263.3468751604.

The spelling of 18263521 in words is "eighteen million, two hundred sixty-three thousand, five hundred twenty-one".