123557129 has 2 divisors, whose sum is σ = 123557130. Its totient is φ = 123557128.

The previous prime is 123557123. The next prime is 123557131. The reversal of 123557129 is 921755321.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 96983104 + 26574025 = 9848^2 + 5155^2 .

It is a cyclic number.

It is not a de Polignac number, because 123557129 - 2⁴ = 123557113 is a prime.

Together with 123557131, 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 (123557123) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 61778564 + 61778565.

It is an arithmetic number, because the mean of its divisors is an integer number (61778565).

Almost surely, 2^123557129 is an apocalyptic number.

It is an amenable number.

123557129 is a deficient number, since it is larger than the sum of its proper divisors (1).

123557129 is an equidigital number, since it uses as much as digits as its factorization.

123557129 is an evil number, because the sum of its binary digits is even.

The product of its digits is 18900, while the sum is 35.

The square root of 123557129 is about 11115.6254434917. The cubic root of 123557129 is about 498.0687219345.

The spelling of 123557129 in words is "one hundred twenty-three million, five hundred fifty-seven thousand, one hundred twenty-nine".