1666840 has 32 divisors (see below), whose sum is σ = 4286880. Its totient is φ = 571392.

The previous prime is 1666823. The next prime is 1666843. The reversal of 1666840 is 486661.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1666843) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2697 + ... + 3256.

It is an arithmetic number, because the mean of its divisors is an integer number (133965).

2^1666840 is an apocalyptic number.

1666840 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1666840 is an abundant number, since it is smaller than the sum of its proper divisors (2620040).

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

1666840 is a wasteful number, since it uses less digits than its factorization.

1666840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5971 (or 5967 counting only the distinct ones).

The product of its (nonzero) digits is 6912, while the sum is 31.

The square root of 1666840 is about 1291.0615787018. The cubic root of 1666840 is about 118.5672201950.

The spelling of 1666840 in words is "one million, six hundred sixty-six thousand, eight hundred forty".