665615556 has 30 divisors (see below), whose sum is σ = 1740051390. Its totient is φ = 221871744.

The previous prime is 665615549. The next prime is 665615593. The reversal of 665615556 is 655516566.

It can be written as a sum of positive squares in only one way, i.e., 333792900 + 331822656 = 18270^2 + 18216^2 .

It is a Smith number, since the sum of its digits (45) coincides with the sum of the digits of its prime factors.

It is an unprimeable number.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 1026861 + ... + 1027508.

It is an arithmetic number, because the mean of its divisors is an integer number (58001713).

Almost surely, 2^665615556 is an apocalyptic number.

It is an amenable number.

665615556 is an abundant number, since it is smaller than the sum of its proper divisors (1074435834).

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

665615556 is a wasteful number, since it uses less digits than its factorization.

665615556 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2054385 (or 2054374 counting only the distinct ones).

The product of its digits is 810000, while the sum is 45.

The square root of 665615556 is about 25799.5262747206. The cubic root of 665615556 is about 873.1211083621.

The spelling of 665615556 in words is "six hundred sixty-five million, six hundred fifteen thousand, five hundred fifty-six".