8721772817 has 2 divisors, whose sum is σ = 8721772818. Its totient is φ = 8721772816.

The previous prime is 8721772789. The next prime is 8721772819. The reversal of 8721772817 is 7182771278.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 8674314496 + 47458321 = 93136^2 + 6889^2 .

It is a cyclic number.

It is not a de Polignac number, because 8721772817 - 2¹⁸ = 8721510673 is a prime.

Together with 8721772819, 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 (8721772819) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4360886408 + 4360886409.

It is an arithmetic number, because the mean of its divisors is an integer number (4360886409).

Almost surely, 2^8721772817 is an apocalyptic number.

It is an amenable number.

8721772817 is a deficient number, since it is larger than the sum of its proper divisors (1).

8721772817 is an equidigital number, since it uses as much as digits as its factorization.

8721772817 is an evil number, because the sum of its binary digits is even.

The product of its digits is 614656, while the sum is 50.

The square root of 8721772817 is about 93390.4321491233. The cubic root of 8721772817 is about 2058.4244100262.

The spelling of 8721772817 in words is "eight billion, seven hundred twenty-one million, seven hundred seventy-two thousand, eight hundred seventeen".