1666638 has 24 divisors (see below), whose sum is σ = 3681288. Its totient is φ = 544752.

The previous prime is 1666627. The next prime is 1666657. The reversal of 1666638 is 8366661.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 81 + ... + 1827.

It is an arithmetic number, because the mean of its divisors is an integer number (153387).

2^1666638 is an apocalyptic number.

1666638 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

1666638 is an abundant number, since it is smaller than the sum of its proper divisors (2014650).

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

1666638 is a wasteful number, since it uses less digits than its factorization.

1666638 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1808 (or 1805 counting only the distinct ones).

The product of its digits is 31104, while the sum is 36.

The square root of 1666638 is about 1290.9833461358. The cubic root of 1666638 is about 118.5624303839.

It can be divided in two parts, 1666 and 638, that added together give a square (2304 = 48²).

The spelling of 1666638 in words is "one million, six hundred sixty-six thousand, six hundred thirty-eight".