6666891 has 64 divisors (see below), whose sum is σ = 12288000. Its totient is φ = 3175200.

The previous prime is 6666883. The next prime is 6666931. The reversal of 6666891 is 1986666.

6666891 = T₁ + T₂ + ... + T₃₄₁.

6666891 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

6666891 is a nontrivial binomial coefficient, being equal to C(343, 3).

It is not a de Polignac number, because 6666891 - 2³ = 6666883 is a prime.

6666891 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (6666841) by changing a digit.

It is the 341-st tetrahedral number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 215046 + ... + 215076.

It is an arithmetic number, because the mean of its divisors is an integer number (192000).

Almost surely, 2^6666891 is an apocalyptic number.

6666891 is a deficient number, since it is larger than the sum of its proper divisors (5621109).

6666891 is a wasteful number, since it uses less digits than its factorization.

6666891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 85 (or 71 counting only the distinct ones).

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

The square root of 6666891 is about 2582.0323390694. The cubic root of 6666891 is about 188.2093168100.

It can be divided in two parts, 6666 and 891, that added together give a palindrome (7557).

The spelling of 6666891 in words is "six million, six hundred sixty-six thousand, eight hundred ninety-one".