8646721 has 2 divisors, whose sum is σ = 8646722. Its totient is φ = 8646720.

The previous prime is 8646719. The next prime is 8646751. The reversal of 8646721 is 1276468.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 7049025 + 1597696 = 2655^2 + 1264^2 .

It is a cyclic number.

It is not a de Polignac number, because 8646721 - 2¹ = 8646719 is a prime.

Together with 8646719, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (8646751) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4323360 + 4323361.

It is an arithmetic number, because the mean of its divisors is an integer number (4323361).

Almost surely, 2^8646721 is an apocalyptic number.

It is an amenable number.

8646721 is a deficient number, since it is larger than the sum of its proper divisors (1).

8646721 is an equidigital number, since it uses as much as digits as its factorization.

8646721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 16128, while the sum is 34.

The square root of 8646721 is about 2940.5307344083. The cubic root of 8646721 is about 205.2503069789.

The spelling of 8646721 in words is "eight million, six hundred forty-six thousand, seven hundred twenty-one".