163951780661 has 2 divisors, whose sum is σ = 163951780662. Its totient is φ = 163951780660.

The previous prime is 163951780621. The next prime is 163951780667. The reversal of 163951780661 is 166087159361.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 160004800036 + 3946980625 = 400006^2 + 62825^2 .

It is an emirp because it is prime and its reverse (166087159361) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 163951780661 - 2¹⁸ = 163951518517 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (163951780667) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 81975890330 + 81975890331.

It is an arithmetic number, because the mean of its divisors is an integer number (81975890331).

Almost surely, 2^163951780661 is an apocalyptic number.

It is an amenable number.

163951780661 is a deficient number, since it is larger than the sum of its proper divisors (1).

163951780661 is an equidigital number, since it uses as much as digits as its factorization.

163951780661 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1632960, while the sum is 53.

The spelling of 163951780661 in words is "one hundred sixty-three billion, nine hundred fifty-one million, seven hundred eighty thousand, six hundred sixty-one".