8717521 has 2 divisors, whose sum is σ = 8717522. Its totient is φ = 8717520.

The previous prime is 8717509. The next prime is 8717531. The reversal of 8717521 is 1257178.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 7182400 + 1535121 = 2680^2 + 1239^2 .

It is a cyclic number.

It is not a de Polignac number, because 8717521 - 2⁷ = 8717393 is a prime.

It is not a weakly prime, because it can be changed into another prime (8717531) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4358760 + 4358761.

It is an arithmetic number, because the mean of its divisors is an integer number (4358761).

Almost surely, 2^8717521 is an apocalyptic number.

It is an amenable number.

8717521 is a deficient number, since it is larger than the sum of its proper divisors (1).

8717521 is an equidigital number, since it uses as much as digits as its factorization.

8717521 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3920, while the sum is 31.

The square root of 8717521 is about 2952.5448345453. The cubic root of 8717521 is about 205.8089865408.

The spelling of 8717521 in words is "eight million, seven hundred seventeen thousand, five hundred twenty-one".