661665060 has 144 divisors (see below), whose sum is σ = 2342785536. Its totient is φ = 148006656.

The previous prime is 661665049. The next prime is 661665061. The reversal of 661665060 is 60566166.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is not an unprimeable number, because it can be changed into a prime (661665061) 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 47 ways as a sum of consecutive naturals, for example, 53634 + ... + 64806.

It is an arithmetic number, because the mean of its divisors is an integer number (16269344).

Almost surely, 2^661665060 is an apocalyptic number.

661665060 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 661665060, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1171392768).

661665060 is an abundant number, since it is smaller than the sum of its proper divisors (1681120476).

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

661665060 is a wasteful number, since it uses less digits than its factorization.

661665060 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11242 (or 11237 counting only the distinct ones).

The product of its (nonzero) digits is 38880, while the sum is 36.

The square root of 661665060 is about 25722.8509306414. The cubic root of 661665060 is about 871.3903255248.

The spelling of 661665060 in words is "six hundred sixty-one million, six hundred sixty-five thousand, sixty".