123555409 has 2 divisors, whose sum is σ = 123555410. Its totient is φ = 123555408.

The previous prime is 123555359. The next prime is 123555413. The reversal of 123555409 is 904555321.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 87890625 + 35664784 = 9375^2 + 5972^2 .

It is a cyclic number.

It is not a de Polignac number, because 123555409 - 2¹⁹ = 123031121 is a prime.

It is not a weakly prime, because it can be changed into another prime (123555449) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 61777704 + 61777705.

It is an arithmetic number, because the mean of its divisors is an integer number (61777705).

Almost surely, 2^123555409 is an apocalyptic number.

It is an amenable number.

123555409 is a deficient number, since it is larger than the sum of its proper divisors (1).

123555409 is an equidigital number, since it uses as much as digits as its factorization.

123555409 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 27000, while the sum is 34.

The square root of 123555409 is about 11115.5480746565. The cubic root of 123555409 is about 498.0664107710.

It can be divided in two parts, 1235 and 55409, that added together give a square (56644 = 238²).

The spelling of 123555409 in words is "one hundred twenty-three million, five hundred fifty-five thousand, four hundred nine".