18271271561 has 2 divisors, whose sum is σ = 18271271562. Its totient is φ = 18271271560.

The previous prime is 18271271539. The next prime is 18271271581. The reversal of 18271271561 is 16517217281.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12064825600 + 6206445961 = 109840^2 + 78781^2 .

It is an emirp because it is prime and its reverse (16517217281) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18271271561 - 2⁶ = 18271271497 is a prime.

It is not a weakly prime, because it can be changed into another prime (18271271581) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9135635780 + 9135635781.

It is an arithmetic number, because the mean of its divisors is an integer number (9135635781).

Almost surely, 2^18271271561 is an apocalyptic number.

It is an amenable number.

18271271561 is a deficient number, since it is larger than the sum of its proper divisors (1).

18271271561 is an equidigital number, since it uses as much as digits as its factorization.

18271271561 is an evil number, because the sum of its binary digits is even.

The product of its digits is 47040, while the sum is 41.

The spelling of 18271271561 in words is "eighteen billion, two hundred seventy-one million, two hundred seventy-one thousand, five hundred sixty-one".