16666661 has 12 divisors (see below), whose sum is σ = 18444972. Its totient is φ = 15048000.

The previous prime is 16666631. The next prime is 16666669.

16666661 is nontrivially palindromic in base 10.

16666661 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 101761 + 16564900 = 319^2 + 4070^2 .

It is not a de Polignac number, because 16666661 - 2⁶ = 16666597 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16666669) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 21521 + ... + 22281.

It is an arithmetic number, because the mean of its divisors is an integer number (1537081).

Almost surely, 2^16666661 is an apocalyptic number.

16666661 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

16666661 is a deficient number, since it is larger than the sum of its proper divisors (1778311).

16666661 is a wasteful number, since it uses less digits than its factorization.

16666661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 964 (or 953 counting only the distinct ones).

The product of its digits is 46656, while the sum is 38.

The square root of 16666661 is about 4082.4822106165. The cubic root of 16666661 is about 255.4364485150.

The spelling of 16666661 in words is "sixteen million, six hundred sixty-six thousand, six hundred sixty-one".