6664621 has 4 divisors (see below), whose sum is σ = 6709500. Its totient is φ = 6619744.

The previous prime is 6664607. The next prime is 6664631. The reversal of 6664621 is 1264666.

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 2842596 + 3822025 = 1686^2 + 1955^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-6664621 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 (6664631) 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, 22216 + ... + 22513.

It is an arithmetic number, because the mean of its divisors is an integer number (1677375).

Almost surely, 2^6664621 is an apocalyptic number.

It is an amenable number.

6664621 is a deficient number, since it is larger than the sum of its proper divisors (44879).

6664621 is a wasteful number, since it uses less digits than its factorization.

6664621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 44878.

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

The square root of 6664621 is about 2581.5927254313. The cubic root of 6664621 is about 188.1879533465.

The spelling of 6664621 in words is "six million, six hundred sixty-four thousand, six hundred twenty-one".