6646621 has 4 divisors (see below), whose sum is σ = 6755644. Its totient is φ = 6537600.

The previous prime is 6646613. The next prime is 6646657. The reversal of 6646621 is 1266466.

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 2295225 + 4351396 = 1515^2 + 2086^2 .

It is a cyclic number.

It is not a de Polignac number, because 6646621 - 2³ = 6646613 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 (6646921) 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, 54420 + ... + 54541.

It is an arithmetic number, because the mean of its divisors is an integer number (1688911).

Almost surely, 2^6646621 is an apocalyptic number.

6646621 is a gapful number since it is divisible by the number (61) formed by its first and last digit.

It is an amenable number.

6646621 is a deficient number, since it is larger than the sum of its proper divisors (109023).

6646621 is a wasteful number, since it uses less digits than its factorization.

6646621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 109022.

The product of its digits is 10368, while the sum is 31.

The square root of 6646621 is about 2578.1041484005. The cubic root of 6646621 is about 188.0183794465.

The spelling of 6646621 in words is "six million, six hundred forty-six thousand, six hundred twenty-one".