163801991 has 2 divisors, whose sum is σ = 163801992. Its totient is φ = 163801990.

The previous prime is 163801973. The next prime is 163801993. The reversal of 163801991 is 199108361.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 163801991 - 2²² = 159607687 is a prime.

Together with 163801993, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (163801993) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 81900995 + 81900996.

It is an arithmetic number, because the mean of its divisors is an integer number (81900996).

Almost surely, 2^163801991 is an apocalyptic number.

163801991 is a deficient number, since it is larger than the sum of its proper divisors (1).

163801991 is an equidigital number, since it uses as much as digits as its factorization.

163801991 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 11664, while the sum is 38.

The square root of 163801991 is about 12798.5151873176. The cubic root of 163801991 is about 547.1499855522.

The spelling of 163801991 in words is "one hundred sixty-three million, eight hundred one thousand, nine hundred ninety-one".