810900721 has 2 divisors, whose sum is σ = 810900722. Its totient is φ = 810900720.

The previous prime is 810900691. The next prime is 810900733. The reversal of 810900721 is 127009018.

810900721 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., 588741696 + 222159025 = 24264^2 + 14905^2 .

It is a cyclic number.

It is not a de Polignac number, because 810900721 - 2⁷ = 810900593 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 810900721.

It is not a weakly prime, because it can be changed into another prime (810900421) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 405450360 + 405450361.

It is an arithmetic number, because the mean of its divisors is an integer number (405450361).

Almost surely, 2^810900721 is an apocalyptic number.

It is an amenable number.

810900721 is a deficient number, since it is larger than the sum of its proper divisors (1).

810900721 is an equidigital number, since it uses as much as digits as its factorization.

810900721 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1008, while the sum is 28.

The square root of 810900721 is about 28476.3185998471. The cubic root of 810900721 is about 932.5151484289.

Adding to 810900721 its reverse (127009018), we get a palindrome (937909739).

The spelling of 810900721 in words is "eight hundred ten million, nine hundred thousand, seven hundred twenty-one".