198851381 has 2 divisors, whose sum is σ = 198851382. Its totient is φ = 198851380.

The previous prime is 198851371. The next prime is 198851383. The reversal of 198851381 is 183158891.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 119552356 + 79299025 = 10934^2 + 8905^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-198851381 is a prime.

It is a super-2 number, since 2×198851381² = 79083743451214322, which contains 22 as substring.

It is a Sophie Germain prime.

Together with 198851383, it forms a pair of twin primes.

It is a Chen 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 (198851383) 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, 99425690 + 99425691.

It is an arithmetic number, because the mean of its divisors is an integer number (99425691).

Almost surely, 2^198851381 is an apocalyptic number.

It is an amenable number.

198851381 is a deficient number, since it is larger than the sum of its proper divisors (1).

198851381 is an equidigital number, since it uses as much as digits as its factorization.

198851381 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 69120, while the sum is 44.

The square root of 198851381 is about 14101.4673349974. The cubic root of 198851381 is about 583.6818701506.

The spelling of 198851381 in words is "one hundred ninety-eight million, eight hundred fifty-one thousand, three hundred eighty-one".