8791721 has 2 divisors, whose sum is σ = 8791722. Its totient is φ = 8791720.

The previous prime is 8791709. The next prime is 8791733. The reversal of 8791721 is 1271978.

It is a balanced prime because it is at equal distance from previous prime (8791709) and next prime (8791733).

It can be written as a sum of positive squares in only one way, i.e., 4791721 + 4000000 = 2189^2 + 2000^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-8791721 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (8791751) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4395860 + 4395861.

It is an arithmetic number, because the mean of its divisors is an integer number (4395861).

Almost surely, 2^8791721 is an apocalyptic number.

It is an amenable number.

8791721 is a deficient number, since it is larger than the sum of its proper divisors (1).

8791721 is an equidigital number, since it uses as much as digits as its factorization.

8791721 is an evil number, because the sum of its binary digits is even.

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

The square root of 8791721 is about 2965.0836413160. The cubic root of 8791721 is about 206.3912584809.

The spelling of 8791721 in words is "eight million, seven hundred ninety-one thousand, seven hundred twenty-one".