663721632 has 144 divisors (see below), whose sum is σ = 2187948672. Its totient is φ = 186923520.

The previous prime is 663721573. The next prime is 663721673. The reversal of 663721632 is 236127366.

663721632 is a `hidden beast` number, since 6 + 637 + 2 + 16 + 3 + 2 = 666.

663721632 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 (144).

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

It is a nude number because it is divisible by every one of its digits.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 140818 + ... + 145454.

It is an arithmetic number, because the mean of its divisors is an integer number (15194088).

Almost surely, 2^663721632 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 663721632, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1093974336).

663721632 is an abundant number, since it is smaller than the sum of its proper divisors (1524227040).

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

663721632 is a wasteful number, since it uses less digits than its factorization.

663721632 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4731 (or 4720 counting only the distinct ones).

The product of its digits is 54432, while the sum is 36.

The square root of 663721632 is about 25762.7955004887. The cubic root of 663721632 is about 872.2922035066.

Adding to 663721632 its reverse (236127366), we get a palindrome (899848998).

The spelling of 663721632 in words is "six hundred sixty-three million, seven hundred twenty-one thousand, six hundred thirty-two".