6667921 has 4 divisors (see below), whose sum is σ = 7180852. Its totient is φ = 6154992.

The previous prime is 6667909. The next prime is 6667931. The reversal of 6667921 is 1297666.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 3845521 + 2822400 = 1961^2 + 1680^2 .

It is a cyclic number.

It is not a de Polignac number, because 6667921 - 2⁵ = 6667889 is a prime.

It is a super-2 number, since 2×6667921² = 88922340924482, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (6667931) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 256446 + ... + 256471.

It is an arithmetic number, because the mean of its divisors is an integer number (1795213).

Almost surely, 2^6667921 is an apocalyptic number.

It is an amenable number.

6667921 is a deficient number, since it is larger than the sum of its proper divisors (512931).

6667921 is a wasteful number, since it uses less digits than its factorization.

6667921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 512930.

The product of its digits is 27216, while the sum is 37.

The square root of 6667921 is about 2582.2317866528. The cubic root of 6667921 is about 188.2190087646.

The spelling of 6667921 in words is "six million, six hundred sixty-seven thousand, nine hundred twenty-one".