171821374561 has 2 divisors, whose sum is σ = 171821374562. Its totient is φ = 171821374560.

The previous prime is 171821374547. The next prime is 171821374589. The reversal of 171821374561 is 165473128171.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 129146078161 + 42675296400 = 359369^2 + 206580^2 .

It is a cyclic number.

It is not a de Polignac number, because 171821374561 - 2¹⁵ = 171821341793 is a prime.

It is not a weakly prime, because it can be changed into another prime (171821377561) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 85910687280 + 85910687281.

It is an arithmetic number, because the mean of its divisors is an integer number (85910687281).

Almost surely, 2^171821374561 is an apocalyptic number.

It is an amenable number.

171821374561 is a deficient number, since it is larger than the sum of its proper divisors (1).

171821374561 is an equidigital number, since it uses as much as digits as its factorization.

171821374561 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 282240, while the sum is 46.

The spelling of 171821374561 in words is "one hundred seventy-one billion, eight hundred twenty-one million, three hundred seventy-four thousand, five hundred sixty-one".