168499991 has 4 divisors (see below), whose sum is σ = 183818184. Its totient is φ = 153181800.

The previous prime is 168499957. The next prime is 168499993. The reversal of 168499991 is 199994861.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 168499991 - 2⁶ = 168499927 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (168499993) 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 in 3 ways as a sum of consecutive naturals, for example, 7659080 + ... + 7659101.

It is an arithmetic number, because the mean of its divisors is an integer number (45954546).

Almost surely, 2^168499991 is an apocalyptic number.

168499991 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

168499991 is a deficient number, since it is larger than the sum of its proper divisors (15318193).

168499991 is a wasteful number, since it uses less digits than its factorization.

168499991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15318192.

The product of its digits is 1259712, while the sum is 56.

The square root of 168499991 is about 12980.7546390801. The cubic root of 168499991 is about 552.3316888680.

The spelling of 168499991 in words is "one hundred sixty-eight million, four hundred ninety-nine thousand, nine hundred ninety-one".