1665540 has 72 divisors (see below), whose sum is σ = 5328960. Its totient is φ = 419904.

The previous prime is 1665533. The next prime is 1665563. The reversal of 1665540 is 455661.

It is a happy number.

1665540 is a `hidden beast` number, since 1 + 6 + 655 + 4 + 0 = 666.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 3177 + ... + 3663.

2^1665540 is an apocalyptic number.

1665540 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1665540, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2664480).

1665540 is an abundant number, since it is smaller than the sum of its proper divisors (3663420).

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

1665540 is a wasteful number, since it uses less digits than its factorization.

1665540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 521 (or 516 counting only the distinct ones).

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

The square root of 1665540 is about 1290.5580188430. The cubic root of 1665540 is about 118.5363879065.

It can be divided in two parts, 16 and 65540, that added together give a palindrome (65556).

The spelling of 1665540 in words is "one million, six hundred sixty-five thousand, five hundred forty".