18320521 has 2 divisors, whose sum is σ = 18320522. Its totient is φ = 18320520.

The previous prime is 18320461. The next prime is 18320539. The reversal of 18320521 is 12502381.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14175225 + 4145296 = 3765^2 + 2036^2 .

It is a cyclic number.

It is not a de Polignac number, because 18320521 - 2¹⁷ = 18189449 is a prime.

It is a super-2 number, since 2×18320521² = 671282979422882, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 18320492 and 18320501.

It is not a weakly prime, because it can be changed into another prime (18320551) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9160260 + 9160261.

It is an arithmetic number, because the mean of its divisors is an integer number (9160261).

Almost surely, 2^18320521 is an apocalyptic number.

It is an amenable number.

18320521 is a deficient number, since it is larger than the sum of its proper divisors (1).

18320521 is an equidigital number, since it uses as much as digits as its factorization.

18320521 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 480, while the sum is 22.

The square root of 18320521 is about 4280.2477732019. The cubic root of 18320521 is about 263.6205570136.

The spelling of 18320521 in words is "eighteen million, three hundred twenty thousand, five hundred twenty-one".