123131320021 has 4 divisors (see below), whose sum is σ = 123313198572. Its totient is φ = 122949441472.

The previous prime is 123131319989. The next prime is 123131320043. The reversal of 123131320021 is 120023131321.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 120023131321 = 907 ⋅132329803.

It can be written as a sum of positive squares in 2 ways, for example, as 113088273796 + 10043046225 = 336286^2 + 100215^2 .

It is a cyclic number.

It is not a de Polignac number, because 123131320021 - 2⁵ = 123131319989 is a prime.

It is a super-2 number, since 2×123131320021² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (123131320051) 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, 90938260 + ... + 90939613.

It is an arithmetic number, because the mean of its divisors is an integer number (30828299643).

Almost surely, 2^123131320021 is an apocalyptic number.

It is an amenable number.

123131320021 is a deficient number, since it is larger than the sum of its proper divisors (181878551).

123131320021 is an equidigital number, since it uses as much as digits as its factorization.

123131320021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 181878550.

The product of its (nonzero) digits is 216, while the sum is 19.

Adding to 123131320021 its reverse (120023131321), we get a palindrome (243154451342).

The spelling of 123131320021 in words is "one hundred twenty-three billion, one hundred thirty-one million, three hundred twenty thousand, twenty-one".