18418337521 has 2 divisors, whose sum is σ = 18418337522. Its totient is φ = 18418337520.

The previous prime is 18418337519. The next prime is 18418337537. The reversal of 18418337521 is 12573381481.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12526086400 + 5892251121 = 111920^2 + 76761^2 .

It is a cyclic number.

It is not a de Polignac number, because 18418337521 - 2¹ = 18418337519 is a prime.

Together with 18418337519, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (18418337501) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9209168760 + 9209168761.

It is an arithmetic number, because the mean of its divisors is an integer number (9209168761).

Almost surely, 2^18418337521 is an apocalyptic number.

It is an amenable number.

18418337521 is a deficient number, since it is larger than the sum of its proper divisors (1).

18418337521 is an equidigital number, since it uses as much as digits as its factorization.

18418337521 is an evil number, because the sum of its binary digits is even.

The product of its digits is 161280, while the sum is 43.

The spelling of 18418337521 in words is "eighteen billion, four hundred eighteen million, three hundred thirty-seven thousand, five hundred twenty-one".