1668355840 has 72 divisors (see below), whose sum is σ = 4025412720. Its totient is φ = 662470656.

The previous prime is 1668355837. The next prime is 1668355841. The reversal of 1668355840 is 485538661.

It is a super-2 number, since 2×1668355840² = 5566822417724211200, which contains 22 as substring.

It is a hoax number, since the sum of its digits (46) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1668355841) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 173232 + ... + 182608.

It is an arithmetic number, because the mean of its divisors is an integer number (55908510).

Almost surely, 2^1668355840 is an apocalyptic number.

1668355840 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 1668355840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2012706360).

1668355840 is an abundant number, since it is smaller than the sum of its proper divisors (2357056880).

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

1668355840 is an equidigital number, since it uses as much as digits as its factorization.

1668355840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9537 (or 9523 counting only the distinct ones).

The product of its (nonzero) digits is 691200, while the sum is 46.

The square root of 1668355840 is about 40845.5118709510. The cubic root of 1668355840 is about 1186.0315135420.

The spelling of 1668355840 in words is "one billion, six hundred sixty-eight million, three hundred fifty-five thousand, eight hundred forty".