1668409920 has 448 divisors, whose sum is σ = 6421282560. Its totient is φ = 406093824.

The previous prime is 1668409877. The next prime is 1668409921. The reversal of 1668409920 is 299048661.

It is a happy number.

It is a super-2 number, since 2×1668409920² = 5567183322308812800, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1668409921) 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, 5434407 + ... + 5434713.

It is an arithmetic number, because the mean of its divisors is an integer number (14333220).

Almost surely, 2^1668409920 is an apocalyptic number.

1668409920 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 1668409920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3210641280).

1668409920 is an abundant number, since it is smaller than the sum of its proper divisors (4752872640).

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

1668409920 is a wasteful number, since it uses less digits than its factorization.

1668409920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 387 (or 371 counting only the distinct ones).

The product of its (nonzero) digits is 186624, while the sum is 45.

The square root of 1668409920 is about 40846.1738722246. The cubic root of 1668409920 is about 1186.0443285322.

The spelling of 1668409920 in words is "one billion, six hundred sixty-eight million, four hundred nine thousand, nine hundred twenty".