8171005721 has 2 divisors, whose sum is σ = 8171005722. Its totient is φ = 8171005720.

The previous prime is 8171005669. The next prime is 8171005723. The reversal of 8171005721 is 1275001718.

8171005721 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 8071225600 + 99780121 = 89840^2 + 9989^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-8171005721 is a prime.

It is a super-2 number, since 2×8171005721² (a number of 21 digits) contains 22 as substring.

Together with 8171005723, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (8171005723) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4085502860 + 4085502861.

It is an arithmetic number, because the mean of its divisors is an integer number (4085502861).

Almost surely, 2^8171005721 is an apocalyptic number.

It is an amenable number.

8171005721 is a deficient number, since it is larger than the sum of its proper divisors (1).

8171005721 is an equidigital number, since it uses as much as digits as its factorization.

8171005721 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3920, while the sum is 32.

The square root of 8171005721 is about 90393.6154880421. The cubic root of 8171005721 is about 2014.1501275925.

The spelling of 8171005721 in words is "eight billion, one hundred seventy-one million, five thousand, seven hundred twenty-one".