8166636521 has 2 divisors, whose sum is σ = 8166636522. Its totient is φ = 8166636520.

The previous prime is 8166636503. The next prime is 8166636557. The reversal of 8166636521 is 1256366618.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 8157702400 + 8934121 = 90320^2 + 2989^2 .

It is a cyclic number.

It is not a de Polignac number, because 8166636521 - 2²² = 8162442217 is a prime.

It is a super-2 number, since 2×8166636521² (a number of 21 digits) contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (8166636721) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4083318260 + 4083318261.

It is an arithmetic number, because the mean of its divisors is an integer number (4083318261).

Almost surely, 2^8166636521 is an apocalyptic number.

8166636521 is the 48305-th centered heptagonal number.

It is an amenable number.

8166636521 is a deficient number, since it is larger than the sum of its proper divisors (1).

8166636521 is an equidigital number, since it uses as much as digits as its factorization.

8166636521 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 311040, while the sum is 44.

The square root of 8166636521 is about 90369.4446204025. Note that the first 3 decimals coincide. The cubic root of 8166636521 is about 2013.7910614809.

The spelling of 8166636521 in words is "eight billion, one hundred sixty-six million, six hundred thirty-six thousand, five hundred twenty-one".