123405555541561 has 2 divisors, whose sum is σ = 123405555541562. Its totient is φ = 123405555541560.

The previous prime is 123405555541537. The next prime is 123405555541591. The reversal of 123405555541561 is 165145555504321.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 120129929744400 + 3275625797161 = 10960380^2 + 1809869^2 .

It is a cyclic number.

It is not a de Polignac number, because 123405555541561 - 2⁵ = 123405555541529 is a prime.

It is a super-2 number, since 2×123405555541561² (a number of 29 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 123405555541499 and 123405555541508.

It is not a weakly prime, because it can be changed into another prime (123405555541591) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 61702777770780 + 61702777770781.

It is an arithmetic number, because the mean of its divisors is an integer number (61702777770781).

Almost surely, 2^{123405555541561} is an apocalyptic number.

It is an amenable number.

123405555541561 is a deficient number, since it is larger than the sum of its proper divisors (1).

123405555541561 is an equidigital number, since it uses as much as digits as its factorization.

123405555541561 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 9000000, while the sum is 52.

The spelling of 123405555541561 in words is "one hundred twenty-three trillion, four hundred five billion, five hundred fifty-five million, five hundred forty-one thousand, five hundred sixty-one".