6639880 has 48 divisors (see below), whose sum is σ = 16232580. Its totient is φ = 2429952.

The previous prime is 6639863. The next prime is 6639881. The reversal of 6639880 is 889366.

It can be written as a sum of positive squares in 6 ways, for example, as 116964 + 6522916 = 342^2 + 2554^2 .

It is a Harshad number since it is a multiple of its sum of digits (40).

It is not an unprimeable number, because it can be changed into a prime (6639881) 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, 58704 + ... + 58816.

Almost surely, 2^6639880 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 6639880, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (8116290).

6639880 is an abundant number, since it is smaller than the sum of its proper divisors (9592700).

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

6639880 is a wasteful number, since it uses less digits than its factorization.

6639880 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 250 (or 133 counting only the distinct ones).

The product of its (nonzero) digits is 62208, while the sum is 40.

The square root of 6639880 is about 2576.7964607241. The cubic root of 6639880 is about 187.9547952276.

The spelling of 6639880 in words is "six million, six hundred thirty-nine thousand, eight hundred eighty".