8671517821 has 2 divisors, whose sum is σ = 8671517822. Its totient is φ = 8671517820.

The previous prime is 8671517819. The next prime is 8671517837. The reversal of 8671517821 is 1287151768.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 8596071225 + 75446596 = 92715^2 + 8686^2 .

It is a cyclic number.

It is not a de Polignac number, because 8671517821 - 2¹ = 8671517819 is a prime.

Together with 8671517819, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (8671557821) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4335758910 + 4335758911.

It is an arithmetic number, because the mean of its divisors is an integer number (4335758911).

Almost surely, 2^8671517821 is an apocalyptic number.

It is an amenable number.

8671517821 is a deficient number, since it is larger than the sum of its proper divisors (1).

8671517821 is an equidigital number, since it uses as much as digits as its factorization.

8671517821 is an evil number, because the sum of its binary digits is even.

The product of its digits is 188160, while the sum is 46.

The square root of 8671517821 is about 93120.9848584088. The cubic root of 8671517821 is about 2054.4632338910.

The spelling of 8671517821 in words is "eight billion, six hundred seventy-one million, five hundred seventeen thousand, eight hundred twenty-one".