661222666 has 16 divisors (see below), whose sum is σ = 1068899328. Its totient is φ = 304959600.

The previous prime is 661222663. The next prime is 661222687. The reversal of 661222666 is 666222166.

It is a happy number.

661222666 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not an unprimeable number, because it can be changed into a prime (661222663) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 30871 + ... + 47701.

It is an arithmetic number, because the mean of its divisors is an integer number (66806208).

Almost surely, 2^661222666 is an apocalyptic number.

661222666 is a deficient number, since it is larger than the sum of its proper divisors (407676662).

661222666 is a wasteful number, since it uses less digits than its factorization.

661222666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18357.

The product of its digits is 62208, while the sum is 37.

The square root of 661222666 is about 25714.2502515628. The cubic root of 661222666 is about 871.1960762879.

The spelling of 661222666 in words is "six hundred sixty-one million, two hundred twenty-two thousand, six hundred sixty-six".