123945908025581 has 2 divisors, whose sum is σ = 123945908025582. Its totient is φ = 123945908025580.

The previous prime is 123945908025539. The next prime is 123945908025617. The reversal of 123945908025581 is 185520809549321.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 91301197287556 + 32644710738025 = 9555166^2 + 5713555^2 .

It is an emirp because it is prime and its reverse (185520809549321) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 123945908025581 - 2⁴⁶ = 53577163847917 is a prime.

It is a super-2 number, since 2×123945908025581² (a number of 29 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (123945908022581) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 61972954012790 + 61972954012791.

It is an arithmetic number, because the mean of its divisors is an integer number (61972954012791).

Almost surely, 2^{123945908025581} is an apocalyptic number.

It is an amenable number.

123945908025581 is a deficient number, since it is larger than the sum of its proper divisors (1).

123945908025581 is an equidigital number, since it uses as much as digits as its factorization.

123945908025581 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 31104000, while the sum is 62.

The spelling of 123945908025581 in words is "one hundred twenty-three trillion, nine hundred forty-five billion, nine hundred eight million, twenty-five thousand, five hundred eighty-one".