661335168 has 128 divisors (see below), whose sum is σ = 1907579520. Its totient is φ = 201793536.

The previous prime is 661335163. The next prime is 661335187. The reversal of 661335168 is 861533166.

It is a tau number, because it is divible by the number of its divisors (128).

It is a Harshad number since it is a multiple of its sum of digits (39).

It is not an unprimeable number, because it can be changed into a prime (661335163) by changing a digit.

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, 683421 + ... + 684387.

It is an arithmetic number, because the mean of its divisors is an integer number (14902965).

Almost surely, 2^661335168 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 661335168, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (953789760).

661335168 is an abundant number, since it is smaller than the sum of its proper divisors (1246244352).

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

661335168 is a wasteful number, since it uses less digits than its factorization.

661335168 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1134 (or 1122 counting only the distinct ones).

The product of its digits is 77760, while the sum is 39.

The square root of 661335168 is about 25716.4377004281. The cubic root of 661335168 is about 871.2454826114.

The spelling of 661335168 in words is "six hundred sixty-one million, three hundred thirty-five thousand, one hundred sixty-eight".