1665905580 has 144 divisors (see below), whose sum is σ = 5248545120. Its totient is φ = 427198464.

The previous prime is 1665905573. The next prime is 1665905597. The reversal of 1665905580 is 855095661.

It is a happy number.

1665905580 is a `hidden beast` number, since 1 + 6 + 6 + 5 + 90 + 558 + 0 = 666.

It is a super-3 number, since 3×1665905580³ (a number of 29 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 1758667 + ... + 1759613.

It is an arithmetic number, because the mean of its divisors is an integer number (36448230).

Almost surely, 2^1665905580 is an apocalyptic number.

1665905580 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 1665905580, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2624272560).

1665905580 is an abundant number, since it is smaller than the sum of its proper divisors (3582639540).

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

1665905580 is a wasteful number, since it uses less digits than its factorization.

1665905580 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1328 (or 1323 counting only the distinct ones).

The product of its (nonzero) digits is 324000, while the sum is 45.

The square root of 1665905580 is about 40815.5066120709. The cubic root of 1665905580 is about 1185.4506004139.

The spelling of 1665905580 in words is "one billion, six hundred sixty-five million, nine hundred five thousand, five hundred eighty".