8617721 has 16 divisors (see below), whose sum is σ = 10272768. Its totient is φ = 7074000.

The previous prime is 8617703. The next prime is 8617753. The reversal of 8617721 is 1277168.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-8617721 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (8611721) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 32636 + ... + 32898.

It is an arithmetic number, because the mean of its divisors is an integer number (642048).

Almost surely, 2^8617721 is an apocalyptic number.

It is an amenable number.

8617721 is a deficient number, since it is larger than the sum of its proper divisors (1655047).

8617721 is a wasteful number, since it uses less digits than its factorization.

8617721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 452.

The product of its digits is 4704, while the sum is 32.

The square root of 8617721 is about 2935.5955102841. The cubic root of 8617721 is about 205.0205888502.

The spelling of 8617721 in words is "eight million, six hundred seventeen thousand, seven hundred twenty-one".