660640240 has 80 divisors (see below), whose sum is σ = 1658393856. Its totient is φ = 243302400.

The previous prime is 660640237. The next prime is 660640259. The reversal of 660640240 is 42046066.

660640240 = 3156² + 3157² + ... + 3220².

It is a tau number, because it is divible by the number of its divisors (80).

It is a junction number, because it is equal to n+sod(n) for n = 660640199 and 660640208.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 666145 + ... + 667135.

Almost surely, 2^660640240 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 660640240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (829196928).

660640240 is an abundant number, since it is smaller than the sum of its proper divisors (997753616).

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

660640240 is a wasteful number, since it uses less digits than its factorization.

660640240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1658 (or 1652 counting only the distinct ones).

The product of its (nonzero) digits is 6912, while the sum is 28.

The square root of 660640240 is about 25702.9227909979. The cubic root of 660640240 is about 870.9402087236.

The spelling of 660640240 in words is "six hundred sixty million, six hundred forty thousand, two hundred forty".