123171725991 has 4 divisors (see below), whose sum is σ = 164228967992. Its totient is φ = 82114483992.

The previous prime is 123171725983. The next prime is 123171726001. The reversal of 123171725991 is 199527171321.

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

It is not a de Polignac number, because 123171725991 - 2³ = 123171725983 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 123171725991.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (123171725921) 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, 20528620996 + ... + 20528621001.

It is an arithmetic number, because the mean of its divisors is an integer number (41057241998).

Almost surely, 2^123171725991 is an apocalyptic number.

123171725991 is a deficient number, since it is larger than the sum of its proper divisors (41057242001).

123171725991 is an equidigital number, since it uses as much as digits as its factorization.

123171725991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 41057242000.

The product of its digits is 238140, while the sum is 48.

The spelling of 123171725991 in words is "one hundred twenty-three billion, one hundred seventy-one million, seven hundred twenty-five thousand, nine hundred ninety-one".