668521920 has 448 divisors, whose sum is σ = 2501798400. Its totient is φ = 149667840.

The previous prime is 668521907. The next prime is 668521927. The reversal of 668521920 is 29125866.

668521920 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (668521927) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 11330851 + ... + 11330909.

Almost surely, 2^668521920 is an apocalyptic number.

668521920 is a gapful number since it is divisible by the number (60) 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 668521920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1250899200).

668521920 is an abundant number, since it is smaller than the sum of its proper divisors (1833276480).

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

668521920 is a wasteful number, since it uses less digits than its factorization.

668521920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 156 (or 146 counting only the distinct ones).

The product of its (nonzero) digits is 51840, while the sum is 39.

The square root of 668521920 is about 25855.7908407382. The cubic root of 668521920 is about 874.3900707226.

The spelling of 668521920 in words is "six hundred sixty-eight million, five hundred twenty-one thousand, nine hundred twenty".