6640000 has 80 divisors (see below), whose sum is σ = 16729020. Its totient is φ = 2624000.

The previous prime is 6639989. The next prime is 6640003. The reversal of 6640000 is 466.

It is a tau number, because it is divible by the number of its divisors (80).

It is a Harshad number since it is a multiple of its sum of digits (16).

It is a nialpdrome in base 10.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6640003) by changing a digit.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 79959 + ... + 80041.

Almost surely, 2^6640000 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 6640000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (8364510).

6640000 is an abundant number, since it is smaller than the sum of its proper divisors (10089020).

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

6640000 is an frugal number, since it uses more digits than its factorization.

6640000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 117 (or 90 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 16.

The square root of 6640000 is about 2576.8197453450. The cubic root of 6640000 is about 187.9559274991.

Adding to 6640000 its reverse (466), we get a palindrome (6640466).

The spelling of 6640000 in words is "six million, six hundred forty thousand".