18249521 has 2 divisors, whose sum is σ = 18249522. Its totient is φ = 18249520.

The previous prime is 18249509. The next prime is 18249529. The reversal of 18249521 is 12594281.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15689521 + 2560000 = 3961^2 + 1600^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18249521 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (18249529) 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, 9124760 + 9124761.

It is an arithmetic number, because the mean of its divisors is an integer number (9124761).

Almost surely, 2^18249521 is an apocalyptic number.

It is an amenable number.

18249521 is a deficient number, since it is larger than the sum of its proper divisors (1).

18249521 is an equidigital number, since it uses as much as digits as its factorization.

18249521 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5760, while the sum is 32.

The square root of 18249521 is about 4271.9458095814. The cubic root of 18249521 is about 263.2795679726.

Adding to 18249521 its product of digits (5760), we get a palindrome (18255281).

The spelling of 18249521 in words is "eighteen million, two hundred forty-nine thousand, five hundred twenty-one".