671721709 has 2 divisors, whose sum is σ = 671721710. Its totient is φ = 671721708.

The previous prime is 671721683. The next prime is 671721719. The reversal of 671721709 is 907127176.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 363016809 + 308704900 = 19053^2 + 17570^2 .

It is a cyclic number.

It is not a de Polignac number, because 671721709 - 2²³ = 663333101 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (671721719) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 335860854 + 335860855.

It is an arithmetic number, because the mean of its divisors is an integer number (335860855).

Almost surely, 2^671721709 is an apocalyptic number.

It is an amenable number.

671721709 is a deficient number, since it is larger than the sum of its proper divisors (1).

671721709 is an equidigital number, since it uses as much as digits as its factorization.

671721709 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 37044, while the sum is 40.

The square root of 671721709 is about 25917.5945836029. The cubic root of 671721709 is about 875.7829004933.

The spelling of 671721709 in words is "six hundred seventy-one million, seven hundred twenty-one thousand, seven hundred nine".