819797857 has 2 divisors, whose sum is σ = 819797858. Its totient is φ = 819797856.

The previous prime is 819797767. The next prime is 819797873. The reversal of 819797857 is 758797918.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 691111521 + 128686336 = 26289^2 + 11344^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-819797857 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 819797795 and 819797804.

It is not a weakly prime, because it can be changed into another prime (819797887) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 409898928 + 409898929.

It is an arithmetic number, because the mean of its divisors is an integer number (409898929).

Almost surely, 2^819797857 is an apocalyptic number.

It is an amenable number.

819797857 is a deficient number, since it is larger than the sum of its proper divisors (1).

819797857 is an equidigital number, since it uses as much as digits as its factorization.

819797857 is an evil number, because the sum of its binary digits is even.

The product of its digits is 8890560, while the sum is 61.

The square root of 819797857 is about 28632.1123391202. The cubic root of 819797857 is about 935.9132438553.

Adding to 819797857 its sum of digits (61), we get a palindrome (819797918).

The spelling of 819797857 in words is "eight hundred nineteen million, seven hundred ninety-seven thousand, eight hundred fifty-seven".