660021984 has 144 divisors (see below), whose sum is σ = 2012224032. Its totient is φ = 204678144.

The previous prime is 660021983. The next prime is 660021997. The reversal of 660021984 is 489120066.

It is a tau number, because it is divible by the number of its divisors (144).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (660021983) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 243742 + ... + 246434.

It is an arithmetic number, because the mean of its divisors is an integer number (13973778).

Almost surely, 2^660021984 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 660021984, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1006112016).

660021984 is an abundant number, since it is smaller than the sum of its proper divisors (1352202048).

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

660021984 is a wasteful number, since it uses less digits than its factorization.

660021984 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2769 (or 2758 counting only the distinct ones).

The product of its (nonzero) digits is 20736, while the sum is 36.

The square root of 660021984 is about 25690.8930167871. The cubic root of 660021984 is about 870.6684359607.

The spelling of 660021984 in words is "six hundred sixty million, twenty-one thousand, nine hundred eighty-four".