8416721 has 2 divisors, whose sum is σ = 8416722. Its totient is φ = 8416720.

The previous prime is 8416697. The next prime is 8416747. The reversal of 8416721 is 1276148.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 7182400 + 1234321 = 2680^2 + 1111^2 .

It is a cyclic number.

It is not a de Polignac number, because 8416721 - 2⁶ = 8416657 is a prime.

It is not a weakly prime, because it can be changed into another prime (8416021) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4208360 + 4208361.

It is an arithmetic number, because the mean of its divisors is an integer number (4208361).

Almost surely, 2^8416721 is an apocalyptic number.

It is an amenable number.

8416721 is a deficient number, since it is larger than the sum of its proper divisors (1).

8416721 is an equidigital number, since it uses as much as digits as its factorization.

8416721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2688, while the sum is 29.

The square root of 8416721 is about 2901.1585616784. The cubic root of 8416721 is about 203.4140642130.

The spelling of 8416721 in words is "eight million, four hundred sixteen thousand, seven hundred twenty-one".