168721 has 4 divisors (see below), whose sum is σ = 192832. Its totient is φ = 144612.

The previous prime is 168719. The next prime is 168731. The reversal of 168721 is 127861.

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: 127861 = 29 ⋅4409.

It is a cyclic number.

It is not a de Polignac number, because 168721 - 2¹ = 168719 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 (168731) 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, 12045 + ... + 12058.

It is an arithmetic number, because the mean of its divisors is an integer number (48208).

2¹⁶⁸⁷²¹ is an apocalyptic number.

It is an amenable number.

168721 is a deficient number, since it is larger than the sum of its proper divisors (24111).

168721 is an equidigital number, since it uses as much as digits as its factorization.

168721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24110.

The product of its digits is 672, while the sum is 25.

The square root of 168721 is about 410.7566189363. The cubic root of 168721 is about 55.2573067601.

The spelling of 168721 in words is "one hundred sixty-eight thousand, seven hundred twenty-one".