8721917 has 2 divisors, whose sum is σ = 8721918. Its totient is φ = 8721916.

The previous prime is 8721913. The next prime is 8721929. The reversal of 8721917 is 7191278.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 7958041 + 763876 = 2821^2 + 874^2 .

It is a cyclic number.

It is not a de Polignac number, because 8721917 - 2² = 8721913 is a prime.

It is a Chen prime.

It is an Ulam number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (8721913) 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, 4360958 + 4360959.

It is an arithmetic number, because the mean of its divisors is an integer number (4360959).

Almost surely, 2^8721917 is an apocalyptic number.

It is an amenable number.

8721917 is a deficient number, since it is larger than the sum of its proper divisors (1).

8721917 is an equidigital number, since it uses as much as digits as its factorization.

8721917 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 7056, while the sum is 35.

The square root of 8721917 is about 2953.2891832667. The cubic root of 8721917 is about 205.8435752834.

The spelling of 8721917 in words is "eight million, seven hundred twenty-one thousand, nine hundred seventeen".