1665406 has 4 divisors (see below), whose sum is σ = 2498112. Its totient is φ = 832702.

The previous prime is 1665343. The next prime is 1665421. The reversal of 1665406 is 6045661.

It is a semiprime because it is the product of two primes.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 416350 + ... + 416353.

It is an arithmetic number, because the mean of its divisors is an integer number (624528).

2^1665406 is an apocalyptic number.

1665406 is a deficient number, since it is larger than the sum of its proper divisors (832706).

1665406 is an equidigital number, since it uses as much as digits as its factorization.

1665406 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 832705.

The product of its (nonzero) digits is 4320, while the sum is 28.

The square root of 1665406 is about 1290.5061022715. The cubic root of 1665406 is about 118.5332088971.

The spelling of 1665406 in words is "one million, six hundred sixty-five thousand, four hundred six".