18396659521 has 2 divisors, whose sum is σ = 18396659522. Its totient is φ = 18396659520.

The previous prime is 18396659483. The next prime is 18396659557. The reversal of 18396659521 is 12595669381.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16728835600 + 1667823921 = 129340^2 + 40839^2 .

It is an emirp because it is prime and its reverse (12595669381) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18396659521 - 2¹¹ = 18396657473 is a prime.

It is not a weakly prime, because it can be changed into another prime (18396659821) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9198329760 + 9198329761.

It is an arithmetic number, because the mean of its divisors is an integer number (9198329761).

Almost surely, 2^18396659521 is an apocalyptic number.

It is an amenable number.

18396659521 is a deficient number, since it is larger than the sum of its proper divisors (1).

18396659521 is an equidigital number, since it uses as much as digits as its factorization.

18396659521 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3499200, while the sum is 55.

The spelling of 18396659521 in words is "eighteen billion, three hundred ninety-six million, six hundred fifty-nine thousand, five hundred twenty-one".