6645720 has 32 divisors (see below), whose sum is σ = 19937520. Its totient is φ = 1772160.

The previous prime is 6645713. The next prime is 6645721. The reversal of 6645720 is 275466.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6645721) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 27571 + ... + 27810.

Almost surely, 2^6645720 is an apocalyptic number.

6645720 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

6645720 is an abundant number, since it is smaller than the sum of its proper divisors (13291800).

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

6645720 is a wasteful number, since it uses less digits than its factorization.

6645720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 55395 (or 55391 counting only the distinct ones).

The product of its (nonzero) digits is 10080, while the sum is 30.

The square root of 6645720 is about 2577.9294016710. The cubic root of 6645720 is about 188.0098832891.

The spelling of 6645720 in words is "six million, six hundred forty-five thousand, seven hundred twenty".