1686136561 has 2 divisors, whose sum is σ = 1686136562. Its totient is φ = 1686136560.

The previous prime is 1686136549. The next prime is 1686136567. The reversal of 1686136561 is 1656316861.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1640655025 + 45481536 = 40505^2 + 6744^2 .

It is an emirp because it is prime and its reverse (1656316861) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1686136561 - 2⁷ = 1686136433 is a prime.

It is not a weakly prime, because it can be changed into another prime (1686136567) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 843068280 + 843068281.

It is an arithmetic number, because the mean of its divisors is an integer number (843068281).

Almost surely, 2^1686136561 is an apocalyptic number.

It is an amenable number.

1686136561 is a deficient number, since it is larger than the sum of its proper divisors (1).

1686136561 is an equidigital number, since it uses as much as digits as its factorization.

1686136561 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 155520, while the sum is 43.

The square root of 1686136561 is about 41062.5932084178. The cubic root of 1686136561 is about 1190.2300619149.

The spelling of 1686136561 in words is "one billion, six hundred eighty-six million, one hundred thirty-six thousand, five hundred sixty-one".