168542209 has 4 divisors (see below), whose sum is σ = 183864240. Its totient is φ = 153220180.

The previous prime is 168542203. The next prime is 168542239. The reversal of 168542209 is 902245861.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 902245861 = 11 ⋅82022351.

It is a cyclic number.

It is not a de Polignac number, because 168542209 - 2³ = 168542201 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (168542201) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7660999 + ... + 7661020.

It is an arithmetic number, because the mean of its divisors is an integer number (45966060).

It is a Proth number, since it is equal to 10287 ⋅ 2¹⁴ + 1 and 10287 < 2¹⁴.

Almost surely, 2^168542209 is an apocalyptic number.

It is an amenable number.

168542209 is a deficient number, since it is larger than the sum of its proper divisors (15322031).

168542209 is a wasteful number, since it uses less digits than its factorization.

168542209 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15322030.

The product of its (nonzero) digits is 34560, while the sum is 37.

The square root of 168542209 is about 12982.3807138752. The cubic root of 168542209 is about 552.3778142751.

The spelling of 168542209 in words is "one hundred sixty-eight million, five hundred forty-two thousand, two hundred nine".