195559981 has 2 divisors, whose sum is σ = 195559982. Its totient is φ = 195559980.

The previous prime is 195559979. The next prime is 195559999. The reversal of 195559981 is 189955591.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 195021225 + 538756 = 13965^2 + 734^2 .

It is a cyclic number.

It is not a de Polignac number, because 195559981 - 2¹ = 195559979 is a prime.

It is a super-2 number, since 2×195559981² = 76487412337440722, which contains 22 as substring.

Together with 195559979, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (195559901) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 97779990 + 97779991.

It is an arithmetic number, because the mean of its divisors is an integer number (97779991).

Almost surely, 2^195559981 is an apocalyptic number.

It is an amenable number.

195559981 is a deficient number, since it is larger than the sum of its proper divisors (1).

195559981 is an equidigital number, since it uses as much as digits as its factorization.

195559981 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 729000, while the sum is 52.

The square root of 195559981 is about 13984.2762057963. The cubic root of 195559981 is about 580.4435578467.

The spelling of 195559981 in words is "one hundred ninety-five million, five hundred fifty-nine thousand, nine hundred eighty-one".