6661212121666 has 8 divisors (see below), whose sum is σ = 9993657973824. Its totient is φ = 3329992797060.

The previous prime is 6661212121651. The next prime is 6661212121763.

6661212121666 is nontrivially palindromic in base 10.

It is a sphenic number, since it is the product of 3 distinct primes.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 306618310 + ... + 306640033.

It is an arithmetic number, because the mean of its divisors is an integer number (1249207246728).

Almost surely, 2^{6661212121666} is an apocalyptic number.

6661212121666 is a deficient number, since it is larger than the sum of its proper divisors (3332445852158).

6661212121666 is a wasteful number, since it uses less digits than its factorization.

6661212121666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 613263776.

The product of its digits is 373248, while the sum is 46.

The spelling of 6661212121666 in words is "six trillion, six hundred sixty-one billion, two hundred twelve million, one hundred twenty-one thousand, six hundred sixty-six".