18503533409 has 2 divisors, whose sum is σ = 18503533410. Its totient is φ = 18503533408.

The previous prime is 18503533403. The next prime is 18503533423. The reversal of 18503533409 is 90433530581.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12841422400 + 5662111009 = 113320^2 + 75247^2 .

It is a cyclic number.

It is not a de Polignac number, because 18503533409 - 2²⁴ = 18486756193 is a prime.

It is a super-2 number, since 2×18503533409² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (18503533403) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9251766704 + 9251766705.

It is an arithmetic number, because the mean of its divisors is an integer number (9251766705).

Almost surely, 2^18503533409 is an apocalyptic number.

It is an amenable number.

18503533409 is a deficient number, since it is larger than the sum of its proper divisors (1).

18503533409 is an equidigital number, since it uses as much as digits as its factorization.

18503533409 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 194400, while the sum is 41.

The spelling of 18503533409 in words is "eighteen billion, five hundred three million, five hundred thirty-three thousand, four hundred nine".