661568688 has 160 divisors (see below), whose sum is σ = 2162004480. Its totient is φ = 191727360.

The previous prime is 661568671. The next prime is 661568701. The reversal of 661568688 is 886865166.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 106270 + ... + 112322.

It is an arithmetic number, because the mean of its divisors is an integer number (13512528).

Almost surely, 2^661568688 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 661568688, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1081002240).

661568688 is an abundant number, since it is smaller than the sum of its proper divisors (1500435792).

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

661568688 is a wasteful number, since it uses less digits than its factorization.

661568688 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6104 (or 6092 counting only the distinct ones).

The product of its digits is 3317760, while the sum is 54.

The square root of 661568688 is about 25720.9775863982. The cubic root of 661568688 is about 871.3480172579.

The spelling of 661568688 in words is "six hundred sixty-one million, five hundred sixty-eight thousand, six hundred eighty-eight".