1665405 has 48 divisors (see below), whose sum is σ = 3504384. Its totient is φ = 714240.

The previous prime is 1665343. The next prime is 1665421. The reversal of 1665405 is 5045661.

It is a happy number.

1665405 is a `hidden beast` number, since 1 + 6 + 654 + 0 + 5 = 666.

It is not a de Polignac number, because 1665405 - 2⁷ = 1665277 is a prime.

1665405 is a lucky number.

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 in 47 ways as a sum of consecutive naturals, for example, 5200 + ... + 5510.

It is an arithmetic number, because the mean of its divisors is an integer number (73008).

2^1665405 is an apocalyptic number.

1665405 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1665405 is an abundant number, since it is smaller than the sum of its proper divisors (1838979).

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

1665405 is a wasteful number, since it uses less digits than its factorization.

1665405 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 346 (or 343 counting only the distinct ones).

The product of its (nonzero) digits is 3600, while the sum is 27.

The square root of 1665405 is about 1290.5057148266. The cubic root of 1665405 is about 118.5331851725.

The spelling of 1665405 in words is "one million, six hundred sixty-five thousand, four hundred five".