661330656 has 360 divisors, whose sum is σ = 2335931136. Its totient is φ = 182891520.

The previous prime is 661330639. The next prime is 661330667. The reversal of 661330656 is 656033166.

It is a happy number.

661330656 is a `hidden beast` number, since 6 + 613 + 30 + 6 + 5 + 6 = 666.

661330656 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a super-3 number, since 3×661330656³ (a number of 27 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a self number, because there is not a number n which added to its sum of digits gives 661330656.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 59 ways as a sum of consecutive naturals, for example, 5207265 + ... + 5207391.

Almost surely, 2^661330656 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 661330656, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1167965568).

661330656 is an abundant number, since it is smaller than the sum of its proper divisors (1674600480).

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

661330656 is a wasteful number, since it uses less digits than its factorization.

661330656 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 204 (or 180 counting only the distinct ones).

The product of its (nonzero) digits is 58320, while the sum is 36.

The square root of 661330656 is about 25716.3499742868. The cubic root of 661330656 is about 871.2435012315.

The spelling of 661330656 in words is "six hundred sixty-one million, three hundred thirty thousand, six hundred fifty-six".