1668890 has 16 divisors (see below), whose sum is σ = 3181032. Its totient is φ = 628224.

The previous prime is 1668889. The next prime is 1668911. The reversal of 1668890 is 988661.

It can be written as a sum of positive squares in 4 ways, for example, as 1666681 + 2209 = 1291^2 + 47^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4739 + ... + 5078.

2^1668890 is an apocalyptic number.

1668890 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

1668890 is a deficient number, since it is larger than the sum of its proper divisors (1512142).

1668890 is a wasteful number, since it uses less digits than its factorization.

1668890 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9841.

The product of its (nonzero) digits is 20736, while the sum is 38.

The square root of 1668890 is about 1291.8552550499. The cubic root of 1668890 is about 118.6158077867.

The spelling of 1668890 in words is "one million, six hundred sixty-eight thousand, eight hundred ninety".