817809681401819 has 2 divisors, whose sum is σ = 817809681401820. Its totient is φ = 817809681401818.

The previous prime is 817809681401813. The next prime is 817809681401857. The reversal of 817809681401819 is 918104186908718.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-817809681401819 is a prime.

It is a super-2 number, since 2×817809681401819² (a number of 31 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (817809681401813) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (31) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 408904840700909 + 408904840700910.

It is an arithmetic number, because the mean of its divisors is an integer number (408904840700910).

Almost surely, 2^{817809681401819} is an apocalyptic number.

817809681401819 is a deficient number, since it is larger than the sum of its proper divisors (1).

817809681401819 is an equidigital number, since it uses as much as digits as its factorization.

817809681401819 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 55738368, while the sum is 71.

The spelling of 817809681401819 in words is "eight hundred seventeen trillion, eight hundred nine billion, six hundred eighty-one million, four hundred one thousand, eight hundred nineteen".