1641666 has 24 divisors (see below), whose sum is σ = 3557520. Its totient is φ = 504816.

The previous prime is 1641659. The next prime is 1641709. The reversal of 1641666 is 6661461.

It is a Smith number, since the sum of its digits (30) coincides with the sum of the digits of its prime factors.

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, 205 + ... + 1823.

It is an arithmetic number, because the mean of its divisors is an integer number (148230).

2^1641666 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1641666, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1778760).

1641666 is an abundant number, since it is smaller than the sum of its proper divisors (1915854).

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

1641666 is a wasteful number, since it uses less digits than its factorization.

1641666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1650 (or 1637 counting only the distinct ones).

The product of its digits is 5184, while the sum is 30.

The square root of 1641666 is about 1281.2751460947. The cubic root of 1641666 is about 117.9672896023.

It can be divided in two parts, 164 and 1666, that added together give a triangular number (1830 = T₆₀).

The spelling of 1641666 in words is "one million, six hundred forty-one thousand, six hundred sixty-six".