16661216661 has 16 divisors (see below), whose sum is σ = 22843684800. Its totient is φ = 10793858688.

The previous prime is 16661216657. The next prime is 16661216669.

16661216661 is nontrivially palindromic in base 10.

It is not a de Polignac number, because 16661216661 - 2² = 16661216657 is a prime.

It is a super-2 number, since 2×16661216661² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16661216669) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2971 + ... + 182568.

It is an arithmetic number, because the mean of its divisors is an integer number (1427730300).

Almost surely, 2^16661216661 is an apocalyptic number.

It is an amenable number.

16661216661 is a deficient number, since it is larger than the sum of its proper divisors (6182468139).

16661216661 is a wasteful number, since it uses less digits than its factorization.

16661216661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 186388.

The product of its digits is 93312, while the sum is 42.

The spelling of 16661216661 in words is "sixteen billion, six hundred sixty-one million, two hundred sixteen thousand, six hundred sixty-one".