126505009 has 2 divisors, whose sum is σ = 126505010. Its totient is φ = 126505008.

The previous prime is 126504979. The next prime is 126505019. The reversal of 126505009 is 900505621.

126505009 = T₉₁₈₂ + T₉₁₈₃ + T₉₁₈₄.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 126495009 + 10000 = 11247^2 + 100^2 .

It is an emirp because it is prime and its reverse (900505621) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 126505009 - 2⁷ = 126504881 is a prime.

It is not a weakly prime, because it can be changed into another prime (126505019) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 63252504 + 63252505.

It is an arithmetic number, because the mean of its divisors is an integer number (63252505).

Almost surely, 2^126505009 is an apocalyptic number.

126505009 is the 9184-th centered triangular number.

It is an amenable number.

126505009 is a deficient number, since it is larger than the sum of its proper divisors (1).

126505009 is an equidigital number, since it uses as much as digits as its factorization.

126505009 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2700, while the sum is 28.

The square root of 126505009 is about 11247.4445542087. Note that the first 3 decimals coincide. The cubic root of 126505009 is about 501.9986785889.

The spelling of 126505009 in words is "one hundred twenty-six million, five hundred five thousand, nine".