6445020666 has 192 divisors, whose sum is σ = 16381854720. Its totient is φ = 1679650560.

The previous prime is 6445020649. The next prime is 6445020667. The reversal of 6445020666 is 6660205446.

It is not an unprimeable number, because it can be changed into a prime (6445020667) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 24505651 + ... + 24505913.

It is an arithmetic number, because the mean of its divisors is an integer number (85322160).

Almost surely, 2^6445020666 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 6445020666, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (8190927360).

6445020666 is an abundant number, since it is smaller than the sum of its proper divisors (9936834054).

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

6445020666 is a wasteful number, since it uses less digits than its factorization.

6445020666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 449 (or 442 counting only the distinct ones).

The product of its (nonzero) digits is 207360, while the sum is 39.

The square root of 6445020666 is about 80280.8860563958. The cubic root of 6445020666 is about 1860.9788529086.

The spelling of 6445020666 in words is "six billion, four hundred forty-five million, twenty thousand, six hundred sixty-six".