1665645 has 8 divisors (see below), whose sum is σ = 2665056. Its totient is φ = 888336.

The previous prime is 1665623. The next prime is 1665647. The reversal of 1665645 is 5465661.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 1665645 - 2⁶ = 1665581 is a prime.

It is a super-3 number, since 3×1665645³ = 13863362876064633375, which contains 333 as substring.

1665645 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1665647) 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, 55507 + ... + 55536.

It is an arithmetic number, because the mean of its divisors is an integer number (333132).

2^1665645 is an apocalyptic number.

1665645 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1665645 is a deficient number, since it is larger than the sum of its proper divisors (999411).

1665645 is a wasteful number, since it uses less digits than its factorization.

1665645 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 111051.

The product of its digits is 21600, while the sum is 33.

The square root of 1665645 is about 1290.5986982792. The cubic root of 1665645 is about 118.5388788022.

The spelling of 1665645 in words is "one million, six hundred sixty-five thousand, six hundred forty-five".