123123155543 has 4 divisors (see below), whose sum is σ = 123124669200. Its totient is φ = 123121641888.

The previous prime is 123123155527. The next prime is 123123155549. The reversal of 123123155543 is 345551321321.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 345551321321 = 17 ⋅20326548313.

It is a cyclic number.

It is not a de Polignac number, because 123123155543 - 2⁴ = 123123155527 is a prime.

It is a super-2 number, since 2×123123155543² (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 (123123155549) 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, 627443 + ... + 799956.

It is an arithmetic number, because the mean of its divisors is an integer number (30781167300).

Almost surely, 2^123123155543 is an apocalyptic number.

123123155543 is a deficient number, since it is larger than the sum of its proper divisors (1513657).

123123155543 is an equidigital number, since it uses as much as digits as its factorization.

123123155543 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1513656.

The product of its digits is 54000, while the sum is 35.

Adding to 123123155543 its reverse (345551321321), we get a palindrome (468674476864).

The spelling of 123123155543 in words is "one hundred twenty-three billion, one hundred twenty-three million, one hundred fifty-five thousand, five hundred forty-three".