666621661198 has 16 divisors (see below), whose sum is σ = 1087366972464. Its totient is φ = 305225815680.

The previous prime is 666621661183. The next prime is 666621661243. The reversal of 666621661198 is 891166126666.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 264951708 + ... + 264954223.

It is an arithmetic number, because the mean of its divisors is an integer number (67960435779).

Almost surely, 2^666621661198 is an apocalyptic number.

666621661198 is a deficient number, since it is larger than the sum of its proper divisors (420745311266).

666621661198 is a wasteful number, since it uses less digits than its factorization.

666621661198 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 529905987.

The product of its digits is 6718464, while the sum is 58.

The spelling of 666621661198 in words is "six hundred sixty-six billion, six hundred twenty-one million, six hundred sixty-one thousand, one hundred ninety-eight".