661185275688 has 192 divisors, whose sum is σ = 2108026512000. Its totient is φ = 188101232640.

The previous prime is 661185275683. The next prime is 661185275759. The reversal of 661185275688 is 886572581166.

661185275688 is a `hidden beast` number, since 6 + 6 + 1 + 18 + 52 + 7 + 568 + 8 = 666.

It is a Cunningham number, because it is equal to 813133²-1.

It is a Harshad number since it is a multiple of its sum of digits (63).

It is not an unprimeable number, because it can be changed into a prime (661185275683) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 87814708 + ... + 87822236.

It is an arithmetic number, because the mean of its divisors is an integer number (10979304750).

Almost surely, 2^661185275688 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 661185275688, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1054013256000).

661185275688 is an abundant number, since it is smaller than the sum of its proper divisors (1446841236312).

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

661185275688 is a wasteful number, since it uses less digits than its factorization.

661185275688 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8033 (or 7782 counting only the distinct ones).

The product of its digits is 38707200, while the sum is 63.

The spelling of 661185275688 in words is "six hundred sixty-one billion, one hundred eighty-five million, two hundred seventy-five thousand, six hundred eighty-eight".