813195781 has 2 divisors, whose sum is σ = 813195782. Its totient is φ = 813195780.

The previous prime is 813195769. The next prime is 813195791. The reversal of 813195781 is 187591318.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 603930625 + 209265156 = 24575^2 + 14466^2 .

It is a cyclic number.

It is not a de Polignac number, because 813195781 - 2¹⁹ = 812671493 is a prime.

It is a super-2 number, since 2×813195781² = 1322574756472399922, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (813195791) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 406597890 + 406597891.

It is an arithmetic number, because the mean of its divisors is an integer number (406597891).

Almost surely, 2^813195781 is an apocalyptic number.

It is an amenable number.

813195781 is a deficient number, since it is larger than the sum of its proper divisors (1).

813195781 is an equidigital number, since it uses as much as digits as its factorization.

813195781 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 60480, while the sum is 43.

The square root of 813195781 is about 28516.5878218275. The cubic root of 813195781 is about 933.3940732438.

The spelling of 813195781 in words is "eight hundred thirteen million, one hundred ninety-five thousand, seven hundred eighty-one".