6644921 has 4 divisors (see below), whose sum is σ = 6661200. Its totient is φ = 6628644.

The previous prime is 6644903. The next prime is 6644933. The reversal of 6644921 is 1294466.

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 6644921 - 2¹⁴ = 6628537 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (6644621) 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, 7511 + ... + 8348.

It is an arithmetic number, because the mean of its divisors is an integer number (1665300).

Almost surely, 2^6644921 is an apocalyptic number.

It is an amenable number.

6644921 is a deficient number, since it is larger than the sum of its proper divisors (16279).

6644921 is a wasteful number, since it uses less digits than its factorization.

6644921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16278.

The product of its digits is 10368, while the sum is 32.

The square root of 6644921 is about 2577.7744276798. The cubic root of 6644921 is about 188.0023483183.

The spelling of 6644921 in words is "six million, six hundred forty-four thousand, nine hundred twenty-one".