194039981 has 2 divisors, whose sum is σ = 194039982. Its totient is φ = 194039980.

The previous prime is 194039977. The next prime is 194039999. The reversal of 194039981 is 189930491.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 177156100 + 16883881 = 13310^2 + 4109^2 .

It is a cyclic number.

It is not a de Polignac number, because 194039981 - 2² = 194039977 is a prime.

It is a super-2 number, since 2×194039981² = 75303028452960722, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (194039941) 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, 97019990 + 97019991.

It is an arithmetic number, because the mean of its divisors is an integer number (97019991).

Almost surely, 2^194039981 is an apocalyptic number.

It is an amenable number.

194039981 is a deficient number, since it is larger than the sum of its proper divisors (1).

194039981 is an equidigital number, since it uses as much as digits as its factorization.

194039981 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 69984, while the sum is 44.

The square root of 194039981 is about 13929.8234375027. The cubic root of 194039981 is about 578.9358022452.

The spelling of 194039981 in words is "one hundred ninety-four million, thirty-nine thousand, nine hundred eighty-one".