6645870 has 144 divisors (see below), whose sum is σ = 22087728. Its totient is φ = 1370880.

The previous prime is 6645857. The next prime is 6645871. The reversal of 6645870 is 785466.

It is a happy number.

6645870 is a `hidden beast` number, since 6 + 645 + 8 + 7 + 0 = 666.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6645871) by changing a digit.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 48442 + ... + 48578.

It is an arithmetic number, because the mean of its divisors is an integer number (153387).

Almost surely, 2^6645870 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 6645870, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (11043864).

6645870 is an abundant number, since it is smaller than the sum of its proper divisors (15441858).

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

6645870 is a wasteful number, since it uses less digits than its factorization.

6645870 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 175 (or 165 counting only the distinct ones).

The product of its (nonzero) digits is 40320, while the sum is 36.

The square root of 6645870 is about 2577.9584946232. The cubic root of 6645870 is about 188.0112977970.

The spelling of 6645870 in words is "six million, six hundred forty-five thousand, eight hundred seventy".