1665664000 has 528 divisors, whose sum is σ = 5610024576. Its totient is φ = 479232000.

The previous prime is 1665663943. The next prime is 1665664001. The reversal of 1665664000 is 4665661.

1665664000 = T₆₅₃₉ + T₆₅₄₀ + ... + T₆₆₁₅.

It is not an unprimeable number, because it can be changed into a prime (1665664001) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 128127994 + ... + 128128006.

Almost surely, 2^1665664000 is an apocalyptic number.

1665664000 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 1665664000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2805012288).

1665664000 is an abundant number, since it is smaller than the sum of its proper divisors (3944360576).

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

1665664000 is a wasteful number, since it uses less digits than its factorization.

1665664000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 79 (or 38 counting only the distinct ones).

The product of its (nonzero) digits is 25920, while the sum is 34.

The square root of 1665664000 is about 40812.5470903251. The cubic root of 1665664000 is about 1185.3932952453.

It can be divided in two parts, 16656 and 64000, that added together give a square (80656 = 284²).

The spelling of 1665664000 in words is "one billion, six hundred sixty-five million, six hundred sixty-four thousand".