1665968640 has 480 divisors, whose sum is σ = 6549491520. Its totient is φ = 359202816.

The previous prime is 1665968617. The next prime is 1665968671. The reversal of 1665968640 is 468695661.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (480).

It is a congruent number.

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 47 ways as a sum of consecutive naturals, for example, 7149964 + ... + 7150196.

It is an arithmetic number, because the mean of its divisors is an integer number (13644774).

Almost surely, 2^1665968640 is an apocalyptic number.

1665968640 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 1665968640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3274745760).

1665968640 is an abundant number, since it is smaller than the sum of its proper divisors (4883522880).

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

1665968640 is a wasteful number, since it uses less digits than its factorization.

1665968640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 292 (or 269 counting only the distinct ones).

The product of its (nonzero) digits is 1866240, while the sum is 51.

The square root of 1665968640 is about 40816.2791052786. The cubic root of 1665968640 is about 1185.4655579586.

The spelling of 1665968640 in words is "one billion, six hundred sixty-five million, nine hundred sixty-eight thousand, six hundred forty".