1668331720 has 128 divisors (see below), whose sum is σ = 4485974400. Its totient is φ = 551219200.

The previous prime is 1668331663. The next prime is 1668331723. The reversal of 1668331720 is 271338661.

It is a self number, because there is not a number n which added to its sum of digits gives 1668331720.

It is not an unprimeable number, because it can be changed into a prime (1668331723) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 213075 + ... + 220765.

It is an arithmetic number, because the mean of its divisors is an integer number (35046675).

Almost surely, 2^1668331720 is an apocalyptic number.

1668331720 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1668331720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2242987200).

1668331720 is an abundant number, since it is smaller than the sum of its proper divisors (2817642680).

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

1668331720 is a wasteful number, since it uses less digits than its factorization.

1668331720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7759 (or 7755 counting only the distinct ones).

The product of its (nonzero) digits is 36288, while the sum is 37.

The square root of 1668331720 is about 40845.2166110060. The cubic root of 1668331720 is about 1186.0257978913.

The spelling of 1668331720 in words is "one billion, six hundred sixty-eight million, three hundred thirty-one thousand, seven hundred twenty".