163218991 has 16 divisors (see below), whose sum is σ = 180774720. Its totient is φ = 146407680.

The previous prime is 163218983. The next prime is 163219027. The reversal of 163218991 is 199812361.

It is a cyclic number.

It is not a de Polignac number, because 163218991 - 2³ = 163218983 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (163218941) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 190921 + ... + 191773.

It is an arithmetic number, because the mean of its divisors is an integer number (11298420).

Almost surely, 2^163218991 is an apocalyptic number.

163218991 is a deficient number, since it is larger than the sum of its proper divisors (17555729).

163218991 is a wasteful number, since it uses less digits than its factorization.

163218991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1266.

The product of its digits is 23328, while the sum is 40.

The square root of 163218991 is about 12775.7188056093. The cubic root of 163218991 is about 546.5000796608.

The spelling of 163218991 in words is "one hundred sixty-three million, two hundred eighteen thousand, nine hundred ninety-one".