666404560 has 80 divisors (see below), whose sum is σ = 1578756096. Its totient is φ = 261563904.

The previous prime is 666404549. The next prime is 666404567. The reversal of 666404560 is 65404666.

It is a tau number, because it is divible by the number of its divisors (80).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666404567) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1086814 + ... + 1087426.

Almost surely, 2^666404560 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 666404560, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (789378048).

666404560 is an abundant number, since it is smaller than the sum of its proper divisors (912351536).

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

666404560 is a wasteful number, since it uses less digits than its factorization.

666404560 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 860 (or 854 counting only the distinct ones).

The product of its (nonzero) digits is 103680, while the sum is 37.

The square root of 666404560 is about 25814.8128019554. The cubic root of 666404560 is about 873.4659640975.

The spelling of 666404560 in words is "six hundred sixty-six million, four hundred four thousand, five hundred sixty".