16666861 has 4 divisors (see below), whose sum is σ = 16688224. Its totient is φ = 16645500.

The previous prime is 16666841. The next prime is 16666873. The reversal of 16666861 is 16866661.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 16666861 - 2⁵ = 16666829 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 (16666841) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9465 + ... + 11086.

It is an arithmetic number, because the mean of its divisors is an integer number (4172056).

Almost surely, 2^16666861 is an apocalyptic number.

It is an amenable number.

16666861 is a deficient number, since it is larger than the sum of its proper divisors (21363).

16666861 is an equidigital number, since it uses as much as digits as its factorization.

16666861 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21362.

The product of its digits is 62208, while the sum is 40.

The square root of 16666861 is about 4082.5067054446. The cubic root of 16666861 is about 255.4374702571.

The spelling of 16666861 in words is "sixteen million, six hundred sixty-six thousand, eight hundred sixty-one".