666123550 has 12 divisors (see below), whose sum is σ = 1238989896. Its totient is φ = 266449400.

The previous prime is 666123547. The next prime is 666123551. The reversal of 666123550 is 55321666.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666123551) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 6661186 + ... + 6661285.

It is an arithmetic number, because the mean of its divisors is an integer number (103249158).

Almost surely, 2^666123550 is an apocalyptic number.

666123550 is a deficient number, since it is larger than the sum of its proper divisors (572866346).

666123550 is a wasteful number, since it uses less digits than its factorization.

666123550 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13322483 (or 13322478 counting only the distinct ones).

The product of its (nonzero) digits is 32400, while the sum is 34.

The square root of 666123550 is about 25809.3694227503. The cubic root of 666123550 is about 873.3431722308.

The spelling of 666123550 in words is "six hundred sixty-six million, one hundred twenty-three thousand, five hundred fifty".