817809681401857 has 2 divisors, whose sum is σ = 817809681401858. Its totient is φ = 817809681401856.

The previous prime is 817809681401819. The next prime is 817809681401899. The reversal of 817809681401857 is 758104186908718.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 803074209582096 + 14735471819761 = 28338564^2 + 3838681^2 .

It is a cyclic number.

It is not a de Polignac number, because 817809681401857 - 2¹⁹ = 817809680877569 is a prime.

It is a super-2 number, since 2×817809681401857² (a number of 31 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 817809681401857.

It is not a weakly prime, because it can be changed into another prime (817809681401357) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 408904840700928 + 408904840700929.

It is an arithmetic number, because the mean of its divisors is an integer number (408904840700929).

Almost surely, 2^{817809681401857} is an apocalyptic number.

It is an amenable number.

817809681401857 is a deficient number, since it is larger than the sum of its proper divisors (1).

817809681401857 is an equidigital number, since it uses as much as digits as its factorization.

817809681401857 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 216760320, while the sum is 73.

The spelling of 817809681401857 in words is "eight hundred seventeen trillion, eight hundred nine billion, six hundred eighty-one million, four hundred one thousand, eight hundred fifty-seven".