6639444 has 36 divisors (see below), whose sum is σ = 19181344. Its totient is φ = 1896912.

The previous prime is 6639439. The next prime is 6639449. The reversal of 6639444 is 4449366.

It is an interprime number because it is at equal distance from previous prime (6639439) and next prime (6639449).

It is a tau number, because it is divible by the number of its divisors (36).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a nude number because it is divisible by every one of its digits.

It is a junction number, because it is equal to n+sod(n) for n = 6639399 and 6639408.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6639449) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 12922 + ... + 13425.

Almost surely, 2^6639444 is an apocalyptic number.

It is an amenable number.

6639444 is an abundant number, since it is smaller than the sum of its proper divisors (12541900).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

6639444 is a wasteful number, since it uses less digits than its factorization.

6639444 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26364 (or 26359 counting only the distinct ones).

The product of its digits is 62208, while the sum is 36.

The square root of 6639444 is about 2576.7118581634. The cubic root of 6639444 is about 187.9506811932.

The spelling of 6639444 in words is "six million, six hundred thirty-nine thousand, four hundred forty-four".