163953991 has 2 divisors, whose sum is σ = 163953992. Its totient is φ = 163953990.

The previous prime is 163953989. The next prime is 163954019. The reversal of 163953991 is 199359361.

It is a weak prime.

It is an emirp because it is prime and its reverse (199359361) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 163953991 - 2¹ = 163953989 is a prime.

It is a super-2 number, since 2×163953991² = 53761822329656162, which contains 22 as substring.

Together with 163953989, 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 (163953901) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 81976995 + 81976996.

It is an arithmetic number, because the mean of its divisors is an integer number (81976996).

Almost surely, 2^163953991 is an apocalyptic number.

163953991 is a deficient number, since it is larger than the sum of its proper divisors (1).

163953991 is an equidigital number, since it uses as much as digits as its factorization.

163953991 is an evil number, because the sum of its binary digits is even.

The product of its digits is 196830, while the sum is 46.

The square root of 163953991 is about 12804.4519992072. The cubic root of 163953991 is about 547.3191757752.

The spelling of 163953991 in words is "one hundred sixty-three million, nine hundred fifty-three thousand, nine hundred ninety-one".