815811901 has 2 divisors, whose sum is σ = 815811902. Its totient is φ = 815811900.

The previous prime is 815811889. The next prime is 815811943. The reversal of 815811901 is 109118518.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 776736900 + 39075001 = 27870^2 + 6251^2 .

It is a cyclic number.

It is not a de Polignac number, because 815811901 - 2⁹ = 815811389 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (815811991) 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, 407905950 + 407905951.

It is an arithmetic number, because the mean of its divisors is an integer number (407905951).

Almost surely, 2^815811901 is an apocalyptic number.

It is an amenable number.

815811901 is a deficient number, since it is larger than the sum of its proper divisors (1).

815811901 is an equidigital number, since it uses as much as digits as its factorization.

815811901 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2880, while the sum is 34.

The square root of 815811901 is about 28562.4211333703. The cubic root of 815811901 is about 934.3939378361.

The spelling of 815811901 in words is "eight hundred fifteen million, eight hundred eleven thousand, nine hundred one".