6615216121666 has 32 divisors (see below), whose sum is σ = 10706850760320. Its totient is φ = 3053708526336.

The previous prime is 6615216121651. The next prime is 6615216121729. The reversal of 6615216121666 is 6661216125166.

It is a super-2 number, since 2×6615216121666² (a number of 26 digits) contains 22 as substring.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 8918275 + ... + 9631513.

It is an arithmetic number, because the mean of its divisors is an integer number (334589086260).

Almost surely, 2^{6615216121666} is an apocalyptic number.

6615216121666 is a deficient number, since it is larger than the sum of its proper divisors (4091634638654).

6615216121666 is a wasteful number, since it uses less digits than its factorization.

6615216121666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 718458.

The product of its digits is 933120, while the sum is 49.

The spelling of 6615216121666 in words is "six trillion, six hundred fifteen billion, two hundred sixteen million, one hundred twenty-one thousand, six hundred sixty-six".