665640750 has 64 divisors (see below), whose sum is σ = 1672317504. Its totient is φ = 176342400.

The previous prime is 665640719. The next prime is 665640751. The reversal of 665640750 is 57046566.

It is a junction number, because it is equal to n+sod(n) for n = 665640699 and 665640708.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (665640751) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 114924 + ... + 120576.

It is an arithmetic number, because the mean of its divisors is an integer number (26129961).

Almost surely, 2^665640750 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 665640750, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (836158752).

665640750 is an abundant number, since it is smaller than the sum of its proper divisors (1006676754).

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

665640750 is a wasteful number, since it uses less digits than its factorization.

665640750 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5830 (or 5820 counting only the distinct ones).

The product of its (nonzero) digits is 151200, while the sum is 39.

The square root of 665640750 is about 25800.0145348796. The cubic root of 665640750 is about 873.1321242984.

The spelling of 665640750 in words is "six hundred sixty-five million, six hundred forty thousand, seven hundred fifty".