123188561 has 2 divisors, whose sum is σ = 123188562. Its totient is φ = 123188560.

The previous prime is 123188557. The next prime is 123188563. The reversal of 123188561 is 165881321.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 94458961 + 28729600 = 9719^2 + 5360^2 .

It is a cyclic number.

It is not a de Polignac number, because 123188561 - 2² = 123188557 is a prime.

It is a super-2 number, since 2×123188561² = 30350843122501442, which contains 22 as substring.

Together with 123188563, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (123188563) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 61594280 + 61594281.

It is an arithmetic number, because the mean of its divisors is an integer number (61594281).

Almost surely, 2^123188561 is an apocalyptic number.

It is an amenable number.

123188561 is a deficient number, since it is larger than the sum of its proper divisors (1).

123188561 is an equidigital number, since it uses as much as digits as its factorization.

123188561 is an evil number, because the sum of its binary digits is even.

The product of its digits is 11520, while the sum is 35.

The square root of 123188561 is about 11099.0342372659. The cubic root of 123188561 is about 497.5729862701.

The spelling of 123188561 in words is "one hundred twenty-three million, one hundred eighty-eight thousand, five hundred sixty-one".