123138121 has 2 divisors, whose sum is σ = 123138122. Its totient is φ = 123138120.

The previous prime is 123138017. The next prime is 123138131. The reversal of 123138121 is 121831321.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 93315600 + 29822521 = 9660^2 + 5461^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-123138121 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 123138092 and 123138101.

It is not a weakly prime, because it can be changed into another prime (123138131) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 61569060 + 61569061.

It is an arithmetic number, because the mean of its divisors is an integer number (61569061).

Almost surely, 2^123138121 is an apocalyptic number.

It is an amenable number.

123138121 is a deficient number, since it is larger than the sum of its proper divisors (1).

123138121 is an equidigital number, since it uses as much as digits as its factorization.

123138121 is an evil number, because the sum of its binary digits is even.

The product of its digits is 288, while the sum is 22.

The square root of 123138121 is about 11096.7617348486. The cubic root of 123138121 is about 497.5050659821.

Adding to 123138121 its reverse (121831321), we get a palindrome (244969442).

The spelling of 123138121 in words is "one hundred twenty-three million, one hundred thirty-eight thousand, one hundred twenty-one".