8399493721 has 2 divisors, whose sum is σ = 8399493722. Its totient is φ = 8399493720.

The previous prime is 8399493653. The next prime is 8399493731. The reversal of 8399493721 is 1273949938.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 7415793225 + 983700496 = 86115^2 + 31364^2 .

It is a cyclic number.

It is not a de Polignac number, because 8399493721 - 2⁷ = 8399493593 is a prime.

It is not a weakly prime, because it can be changed into another prime (8399493731) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4199746860 + 4199746861.

It is an arithmetic number, because the mean of its divisors is an integer number (4199746861).

Almost surely, 2^8399493721 is an apocalyptic number.

It is an amenable number.

8399493721 is a deficient number, since it is larger than the sum of its proper divisors (1).

8399493721 is an equidigital number, since it uses as much as digits as its factorization.

8399493721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2939328, while the sum is 55.

The square root of 8399493721 is about 91648.7518791173. The cubic root of 8399493721 is about 2032.7518731162.

The spelling of 8399493721 in words is "eight billion, three hundred ninety-nine million, four hundred ninety-three thousand, seven hundred twenty-one".