6646021 has 4 divisors (see below), whose sum is σ = 6661600. Its totient is φ = 6630444.

The previous prime is 6646019. The next prime is 6646039. The reversal of 6646021 is 1206466.

It is a happy number.

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 6646021 - 2¹ = 6646019 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 (6646001) 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, 7131 + ... + 8008.

It is an arithmetic number, because the mean of its divisors is an integer number (1665400).

Almost surely, 2^6646021 is an apocalyptic number.

It is an amenable number.

6646021 is a deficient number, since it is larger than the sum of its proper divisors (15579).

6646021 is a wasteful number, since it uses less digits than its factorization.

6646021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15578.

The product of its (nonzero) digits is 1728, while the sum is 25.

The square root of 6646021 is about 2577.9877811968. The cubic root of 6646021 is about 188.0127217134.

The spelling of 6646021 in words is "six million, six hundred forty-six thousand, twenty-one".