817820161 has 2 divisors, whose sum is σ = 817820162. Its totient is φ = 817820160.

The previous prime is 817820123. The next prime is 817820167. The reversal of 817820161 is 161028718.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 531025936 + 286794225 = 23044^2 + 16935^2 .

It is a cyclic number.

It is not a de Polignac number, because 817820161 - 2¹⁵ = 817787393 is a prime.

It is not a weakly prime, because it can be changed into another prime (817820167) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 408910080 + 408910081.

It is an arithmetic number, because the mean of its divisors is an integer number (408910081).

Almost surely, 2^817820161 is an apocalyptic number.

It is an amenable number.

817820161 is a deficient number, since it is larger than the sum of its proper divisors (1).

817820161 is an equidigital number, since it uses as much as digits as its factorization.

817820161 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5376, while the sum is 34.

The square root of 817820161 is about 28597.5551577403. Note that the first 3 decimals coincide. The cubic root of 817820161 is about 935.1600328513.

Adding to 817820161 its reverse (161028718), we get a palindrome (978848879).

The spelling of 817820161 in words is "eight hundred seventeen million, eight hundred twenty thousand, one hundred sixty-one".