1806640 has 40 divisors (see below), whose sum is σ = 4584528. Its totient is φ = 656640.

The previous prime is 1806631. The next prime is 1806643. The reversal of 1806640 is 466081.

It is a tau number, because it is divible by the number of its divisors (40).

It is a Smith number, since the sum of its digits (25) coincides with the sum of the digits of its prime factors.

It is not an unprimeable number, because it can be changed into a prime (1806643) 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, 147 + ... + 1906.

2^1806640 is an apocalyptic number.

1806640 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 1806640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2292264).

1806640 is an abundant number, since it is smaller than the sum of its proper divisors (2777888).

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

1806640 is a wasteful number, since it uses less digits than its factorization.

1806640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2077 (or 2071 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 25.

The square root of 1806640 is about 1344.1130904801. The cubic root of 1806640 is about 121.7934334788.

The spelling of 1806640 in words is "one million, eight hundred six thousand, six hundred forty".