661065544818 has 96 divisors (see below), whose sum is σ = 1645170808320. Its totient is φ = 187926036480.

The previous prime is 661065544801. The next prime is 661065544829. The reversal of 661065544818 is 818445560166.

It is a happy number.

661065544818 is a `hidden beast` number, since 6 + 6 + 1 + 0 + 6 + 554 + 4 + 81 + 8 = 666.

It is a hoax number, since the sum of its digits (54) coincides with the sum of the digits of its distinct prime factors.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 29488798 + ... + 29511206.

It is an arithmetic number, because the mean of its divisors is an integer number (17137195920).

Almost surely, 2^661065544818 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 661065544818, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (822585404160).

661065544818 is an abundant number, since it is smaller than the sum of its proper divisors (984105263502).

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

661065544818 is a wasteful number, since it uses less digits than its factorization.

661065544818 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23592 (or 23589 counting only the distinct ones).

The product of its (nonzero) digits is 5529600, while the sum is 54.

The spelling of 661065544818 in words is "six hundred sixty-one billion, sixty-five million, five hundred forty-four thousand, eight hundred eighteen".