126666561 has 24 divisors (see below), whose sum is σ = 196352832. Its totient is φ = 71150400.

The previous prime is 126666557. The next prime is 126666563. The reversal of 126666561 is 165666621.

It is not a de Polignac number, because 126666561 - 2² = 126666557 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (126666563) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 77331 + ... + 78951.

It is an arithmetic number, because the mean of its divisors is an integer number (8181368).

Almost surely, 2^126666561 is an apocalyptic number.

It is an amenable number.

126666561 is a deficient number, since it is larger than the sum of its proper divisors (69686271).

126666561 is an equidigital number, since it uses as much as digits as its factorization.

126666561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1753 (or 1692 counting only the distinct ones).

The product of its digits is 77760, while the sum is 39.

The square root of 126666561 is about 11254.6239830569. The cubic root of 126666561 is about 502.2122785442.

The spelling of 126666561 in words is "one hundred twenty-six million, six hundred sixty-six thousand, five hundred sixty-one".