665520640 has 160 divisors (see below), whose sum is σ = 1697034240. Its totient is φ = 249790464.

The previous prime is 665520637. The next prime is 665520659. The reversal of 665520640 is 46025566.

It is a tau number, because it is divible by the number of its divisors (160).

It is a junction number, because it is equal to n+sod(n) for n = 665520596 and 665520605.

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 15 ways as a sum of consecutive naturals, for example, 5240257 + ... + 5240383.

It is an arithmetic number, because the mean of its divisors is an integer number (10606464).

Almost surely, 2^665520640 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 665520640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (848517120).

665520640 is an abundant number, since it is smaller than the sum of its proper divisors (1031513600).

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

665520640 is a wasteful number, since it uses less digits than its factorization.

665520640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 262 (or 246 counting only the distinct ones).

The product of its (nonzero) digits is 43200, while the sum is 34.

The square root of 665520640 is about 25797.6867179986. The cubic root of 665520640 is about 873.0796043729.

The spelling of 665520640 in words is "six hundred sixty-five million, five hundred twenty thousand, six hundred forty".