666505560 has 128 divisors (see below), whose sum is σ = 2405491200. Its totient is φ = 144322560.

The previous prime is 666505537. The next prime is 666505561. The reversal of 666505560 is 65505666.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666505561) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 4921 + ... + 36840.

It is an arithmetic number, because the mean of its divisors is an integer number (18792900).

Almost surely, 2^666505560 is an apocalyptic number.

666505560 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 666505560, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1202745600).

666505560 is an abundant number, since it is smaller than the sum of its proper divisors (1738985640).

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

666505560 is a wasteful number, since it uses less digits than its factorization.

666505560 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 41801 (or 41797 counting only the distinct ones).

The product of its (nonzero) digits is 162000, while the sum is 39.

The square root of 666505560 is about 25816.7689690248. The cubic root of 666505560 is about 873.5100892486.

The spelling of 666505560 in words is "six hundred sixty-six million, five hundred five thousand, five hundred sixty".