1665761860 has 72 divisors (see below), whose sum is σ = 4118446080. Its totient is φ = 564209856.

The previous prime is 1665761833. The next prime is 1665761873. The reversal of 1665761860 is 681675661.

It is a self number, because there is not a number n which added to its sum of digits gives 1665761860.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 71101 + ... + 91579.

It is an arithmetic number, because the mean of its divisors is an integer number (57200640).

Almost surely, 2^1665761860 is an apocalyptic number.

1665761860 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 1665761860, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2059223040).

1665761860 is an abundant number, since it is smaller than the sum of its proper divisors (2452684220).

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

1665761860 is a wasteful number, since it uses less digits than its factorization.

1665761860 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20585 (or 20576 counting only the distinct ones).

The product of its (nonzero) digits is 362880, while the sum is 46.

The square root of 1665761860 is about 40813.7459687297. The cubic root of 1665761860 is about 1185.4165092741.

The spelling of 1665761860 in words is "one billion, six hundred sixty-five million, seven hundred sixty-one thousand, eight hundred sixty".