1665885780 has 288 divisors, whose sum is σ = 5688603648. Its totient is φ = 391910400.

The previous prime is 1665885763. The next prime is 1665885787. The reversal of 1665885780 is 875885661.

1665885780 is a `hidden beast` number, since 1 + 6 + 6 + 588 + 57 + 8 + 0 = 666.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1665885787) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 6147045 + ... + 6147315.

It is an arithmetic number, because the mean of its divisors is an integer number (19752096).

Almost surely, 2^1665885780 is an apocalyptic number.

1665885780 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 1665885780, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2844301824).

1665885780 is an abundant number, since it is smaller than the sum of its proper divisors (4022717868).

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

1665885780 is a wasteful number, since it uses less digits than its factorization.

1665885780 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 407 (or 402 counting only the distinct ones).

The product of its (nonzero) digits is 3225600, while the sum is 54.

The square root of 1665885780 is about 40815.2640564777. The cubic root of 1665885780 is about 1185.4459038663.

The spelling of 1665885780 in words is "one billion, six hundred sixty-five million, eight hundred eighty-five thousand, seven hundred eighty".