168125720021 has 4 divisors (see below), whose sum is σ = 192143680032. Its totient is φ = 144107760012.

The previous prime is 168125720011. The next prime is 168125720027. The reversal of 168125720021 is 120027521861.

168125720021 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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.

It is a cyclic number.

It is not a de Polignac number, because 168125720021 - 2²² = 168121525717 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (168125720027) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 12008979995 + ... + 12008980008.

It is an arithmetic number, because the mean of its divisors is an integer number (48035920008).

Almost surely, 2^168125720021 is an apocalyptic number.

It is an amenable number.

168125720021 is a deficient number, since it is larger than the sum of its proper divisors (24017960011).

168125720021 is an equidigital number, since it uses as much as digits as its factorization.

168125720021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24017960010.

The product of its (nonzero) digits is 13440, while the sum is 35.

The spelling of 168125720021 in words is "one hundred sixty-eight billion, one hundred twenty-five million, seven hundred twenty thousand, twenty-one".