18987521233 has 2 divisors, whose sum is σ = 18987521234. Its totient is φ = 18987521232.

The previous prime is 18987521209. The next prime is 18987521239. The reversal of 18987521233 is 33212578981.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13498489489 + 5489031744 = 116183^2 + 74088^2 .

It is an emirp because it is prime and its reverse (33212578981) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18987521233 is a prime.

It is not a weakly prime, because it can be changed into another prime (18987521239) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9493760616 + 9493760617.

It is an arithmetic number, because the mean of its divisors is an integer number (9493760617).

Almost surely, 2^18987521233 is an apocalyptic number.

It is an amenable number.

18987521233 is a deficient number, since it is larger than the sum of its proper divisors (1).

18987521233 is an equidigital number, since it uses as much as digits as its factorization.

18987521233 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 725760, while the sum is 49.

The spelling of 18987521233 in words is "eighteen billion, nine hundred eighty-seven million, five hundred twenty-one thousand, two hundred thirty-three".