665646624 has 72 divisors (see below), whose sum is σ = 1907942400. Its totient is φ = 220123008.

The previous prime is 665646593. The next prime is 665646643. The reversal of 665646624 is 426646566.

665646624 is a `hidden beast` number, since 6 + 6 + 564 + 66 + 24 = 666.

665646624 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a tau number, because it is divible by the number of its divisors (72).

It is a self number, because there is not a number n which added to its sum of digits gives 665646624.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 27477 + ... + 45675.

It is an arithmetic number, because the mean of its divisors is an integer number (26499200).

Almost surely, 2^665646624 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 665646624, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (953971200).

665646624 is an abundant number, since it is smaller than the sum of its proper divisors (1242295776).

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

665646624 is a wasteful number, since it uses less digits than its factorization.

665646624 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18342 (or 18331 counting only the distinct ones).

The product of its digits is 1244160, while the sum is 45.

The square root of 665646624 is about 25800.1283717737. The cubic root of 665646624 is about 873.1346926323.

The spelling of 665646624 in words is "six hundred sixty-five million, six hundred forty-six thousand, six hundred twenty-four".