18261186521 has 2 divisors, whose sum is σ = 18261186522. Its totient is φ = 18261186520.

The previous prime is 18261186511. The next prime is 18261186529. The reversal of 18261186521 is 12568116281.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15824382025 + 2436804496 = 125795^2 + 49364^2 .

It is a cyclic number.

It is not a de Polignac number, because 18261186521 - 2⁶ = 18261186457 is a prime.

It is not a weakly prime, because it can be changed into another prime (18261186529) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9130593260 + 9130593261.

It is an arithmetic number, because the mean of its divisors is an integer number (9130593261).

Almost surely, 2^18261186521 is an apocalyptic number.

It is an amenable number.

18261186521 is a deficient number, since it is larger than the sum of its proper divisors (1).

18261186521 is an equidigital number, since it uses as much as digits as its factorization.

18261186521 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 46080, while the sum is 41.

The spelling of 18261186521 in words is "eighteen billion, two hundred sixty-one million, one hundred eighty-six thousand, five hundred twenty-one".