6646661 has 4 divisors (see below), whose sum is σ = 7596192. Its totient is φ = 5697132.

The previous prime is 6646657. The next prime is 6646663. The reversal of 6646661 is 1666466.

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 not a de Polignac number, because 6646661 - 2² = 6646657 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 (6646663) 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, 474755 + ... + 474768.

It is an arithmetic number, because the mean of its divisors is an integer number (1899048).

Almost surely, 2^6646661 is an apocalyptic number.

It is an amenable number.

6646661 is a deficient number, since it is larger than the sum of its proper divisors (949531).

6646661 is an equidigital number, since it uses as much as digits as its factorization.

6646661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 949530.

The product of its digits is 31104, while the sum is 35.

The square root of 6646661 is about 2578.1119060274. Note that the first 3 decimals coincide. The cubic root of 6646661 is about 188.0187566166.

The spelling of 6646661 in words is "six million, six hundred forty-six thousand, six hundred sixty-one".