8397721 has 2 divisors, whose sum is σ = 8397722. Its totient is φ = 8397720.

The previous prime is 8397709. The next prime is 8397751. The reversal of 8397721 is 1277938.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 7485696 + 912025 = 2736^2 + 955^2 .

It is a cyclic number.

It is not a de Polignac number, because 8397721 - 2⁹ = 8397209 is a prime.

It is not a weakly prime, because it can be changed into another prime (8397751) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4198860 + 4198861.

It is an arithmetic number, because the mean of its divisors is an integer number (4198861).

Almost surely, 2^8397721 is an apocalyptic number.

It is an amenable number.

8397721 is a deficient number, since it is larger than the sum of its proper divisors (1).

8397721 is an equidigital number, since it uses as much as digits as its factorization.

8397721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 21168, while the sum is 37.

The square root of 8397721 is about 2897.8821577145. The cubic root of 8397721 is about 203.2608858327.

The spelling of 8397721 in words is "eight million, three hundred ninety-seven thousand, seven hundred twenty-one".