661550656 has 112 divisors (see below), whose sum is σ = 1491130368. Its totient is φ = 288921600.

The previous prime is 661550653. The next prime is 661550671. The reversal of 661550656 is 656055166.

661550656 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not an unprimeable number, because it can be changed into a prime (661550651) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3463521 + ... + 3463711.

It is an arithmetic number, because the mean of its divisors is an integer number (13313664).

Almost surely, 2^661550656 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 661550656, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (745565184).

661550656 is an abundant number, since it is smaller than the sum of its proper divisors (829579712).

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

661550656 is a wasteful number, since it uses less digits than its factorization.

661550656 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 420 (or 410 counting only the distinct ones).

The product of its (nonzero) digits is 162000, while the sum is 40.

The square root of 661550656 is about 25720.6270530094. The cubic root of 661550656 is about 871.3401005742.

The spelling of 661550656 in words is "six hundred sixty-one million, five hundred fifty thousand, six hundred fifty-six".