1666820 has 12 divisors (see below), whose sum is σ = 3500364. Its totient is φ = 666720.

The previous prime is 1666811. The next prime is 1666823. The reversal of 1666820 is 286661.

It can be written as a sum of positive squares in 2 ways, for example, as 1098304 + 568516 = 1048^2 + 754^2 .

It is not an unprimeable number, because it can be changed into a prime (1666823) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 41651 + ... + 41690.

It is an arithmetic number, because the mean of its divisors is an integer number (291697).

2^1666820 is an apocalyptic number.

1666820 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1666820 is an abundant number, since it is smaller than the sum of its proper divisors (1833544).

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

1666820 is a wasteful number, since it uses less digits than its factorization.

1666820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 83350 (or 83348 counting only the distinct ones).

The product of its (nonzero) digits is 3456, while the sum is 29.

The square root of 1666820 is about 1291.0538331146. The cubic root of 1666820 is about 118.5667459736.

The spelling of 1666820 in words is "one million, six hundred sixty-six thousand, eight hundred twenty".