665561260 has 144 divisors (see below), whose sum is σ = 1817315136. Its totient is φ = 199355904.

The previous prime is 665561257. The next prime is 665561261. The reversal of 665561260 is 62165566.

It is not an unprimeable number, because it can be changed into a prime (665561261) 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, 656514 + ... + 657526.

It is an arithmetic number, because the mean of its divisors is an integer number (12620244).

Almost surely, 2^665561260 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 665561260, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (908657568).

665561260 is an abundant number, since it is smaller than the sum of its proper divisors (1151753876).

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

665561260 is a wasteful number, since it uses less digits than its factorization.

665561260 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1080 (or 1059 counting only the distinct ones).

The product of its (nonzero) digits is 64800, while the sum is 37.

The square root of 665561260 is about 25798.4739858775. The cubic root of 665561260 is about 873.0973667932.

The spelling of 665561260 in words is "six hundred sixty-five million, five hundred sixty-one thousand, two hundred sixty".