6721666 has 16 divisors (see below), whose sum is σ = 11579904. Its totient is φ = 2866464.

The previous prime is 6721661. The next prime is 6721667. The reversal of 6721666 is 6661276.

It is not an unprimeable number, because it can be changed into a prime (6721661) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2046 + ... + 4198.

It is an arithmetic number, because the mean of its divisors is an integer number (723744).

Almost surely, 2^6721666 is an apocalyptic number.

6721666 is a deficient number, since it is larger than the sum of its proper divisors (4858238).

6721666 is a wasteful number, since it uses less digits than its factorization.

6721666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2385.

The product of its digits is 18144, while the sum is 34.

The square root of 6721666 is about 2592.6175961757. The cubic root of 6721666 is about 188.7233525237.

The spelling of 6721666 in words is "six million, seven hundred twenty-one thousand, six hundred sixty-six".