1871636861 has 2 divisors, whose sum is σ = 1871636862. Its totient is φ = 1871636860.

The previous prime is 1871636843. The next prime is 1871636863. The reversal of 1871636861 is 1686361781.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1366780900 + 504855961 = 36970^2 + 22469^2 .

It is a cyclic number.

It is not a de Polignac number, because 1871636861 - 2¹⁴ = 1871620477 is a prime.

Together with 1871636863, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1871636863) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 935818430 + 935818431.

It is an arithmetic number, because the mean of its divisors is an integer number (935818431).

Almost surely, 2^1871636861 is an apocalyptic number.

It is an amenable number.

1871636861 is a deficient number, since it is larger than the sum of its proper divisors (1).

1871636861 is an equidigital number, since it uses as much as digits as its factorization.

1871636861 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 290304, while the sum is 47.

The square root of 1871636861 is about 43262.4185754796. The cubic root of 1871636861 is about 1232.3683324545.

The spelling of 1871636861 in words is "one billion, eight hundred seventy-one million, six hundred thirty-six thousand, eight hundred sixty-one".