168042509 has 4 divisors (see below), whose sum is σ = 169775004. Its totient is φ = 166310016.

The previous prime is 168042503. The next prime is 168042527. The reversal of 168042509 is 905240861.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 905240861 = 7 ⋅129320123.

It can be written as a sum of positive squares in 2 ways, for example, as 52157284 + 115885225 = 7222^2 + 10765^2 .

It is a cyclic number.

It is not a de Polignac number, because 168042509 - 2⁸ = 168042253 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 (168042503) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 866102 + ... + 866295.

It is an arithmetic number, because the mean of its divisors is an integer number (42443751).

Almost surely, 2^168042509 is an apocalyptic number.

It is an amenable number.

168042509 is a deficient number, since it is larger than the sum of its proper divisors (1732495).

168042509 is an equidigital number, since it uses as much as digits as its factorization.

168042509 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1732494.

The product of its (nonzero) digits is 17280, while the sum is 35.

The square root of 168042509 is about 12963.1211133739. The cubic root of 168042509 is about 551.8313706800.

The spelling of 168042509 in words is "one hundred sixty-eight million, forty-two thousand, five hundred nine".