1681668 has 48 divisors (see below), whose sum is σ = 4556160. Its totient is φ = 535392.

The previous prime is 1681661. The next prime is 1681679. The reversal of 1681668 is 8661861.

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

It is not an unprimeable number, because it can be changed into a prime (1681661) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2146 + ... + 2822.

It is an arithmetic number, because the mean of its divisors is an integer number (94920).

2^1681668 is an apocalyptic number.

1681668 is a gapful number since it is divisible by the number (18) 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 1681668, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2278080).

1681668 is an abundant number, since it is smaller than the sum of its proper divisors (2874492).

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

1681668 is a wasteful number, since it uses less digits than its factorization.

1681668 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 713 (or 705 counting only the distinct ones).

The product of its digits is 13824, while the sum is 36.

The square root of 1681668 is about 1296.7914250179. The cubic root of 1681668 is about 118.9177691442.

The spelling of 1681668 in words is "one million, six hundred eighty-one thousand, six hundred sixty-eight".