6990721009 has 2 divisors, whose sum is σ = 6990721010. Its totient is φ = 6990721008.

The previous prime is 6990720941. The next prime is 6990721013. The reversal of 6990721009 is 9001270996.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 3506416225 + 3484304784 = 59215^2 + 59028^2 .

It is a cyclic number.

It is not a de Polignac number, because 6990721009 - 2²⁵ = 6957166577 is a prime.

It is not a weakly prime, because it can be changed into another prime (6990721019) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3495360504 + 3495360505.

It is an arithmetic number, because the mean of its divisors is an integer number (3495360505).

Almost surely, 2^6990721009 is an apocalyptic number.

It is an amenable number.

6990721009 is a deficient number, since it is larger than the sum of its proper divisors (1).

6990721009 is an equidigital number, since it uses as much as digits as its factorization.

6990721009 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 61236, while the sum is 43.

The square root of 6990721009 is about 83610.5316871027. The cubic root of 6990721009 is about 1912.0855675344.

The spelling of 6990721009 in words is "six billion, nine hundred ninety million, seven hundred twenty-one thousand, nine".