721850813 has 2 divisors, whose sum is σ = 721850814. Its totient is φ = 721850812.

The previous prime is 721850771. The next prime is 721850827. The reversal of 721850813 is 318058127.

721850813 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 720546649 + 1304164 = 26843^2 + 1142^2 .

It is an emirp because it is prime and its reverse (318058127) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 721850813 - 2⁸ = 721850557 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (721850873) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 360925406 + 360925407.

It is an arithmetic number, because the mean of its divisors is an integer number (360925407).

Almost surely, 2^721850813 is an apocalyptic number.

It is an amenable number.

721850813 is a deficient number, since it is larger than the sum of its proper divisors (1).

721850813 is an equidigital number, since it uses as much as digits as its factorization.

721850813 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 13440, while the sum is 35.

The square root of 721850813 is about 26867.2814590535. The cubic root of 721850813 is about 897.0482775807.

The spelling of 721850813 in words is "seven hundred twenty-one million, eight hundred fifty thousand, eight hundred thirteen".