665218512 has 180 divisors, whose sum is σ = 2260346400. Its totient is φ = 181754496.

The previous prime is 665218511. The next prime is 665218537. The reversal of 665218512 is 215812566.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (665218511) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 160239 + ... + 164337.

It is an arithmetic number, because the mean of its divisors is an integer number (12557480).

Almost surely, 2^665218512 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 665218512, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1130173200).

665218512 is an abundant number, since it is smaller than the sum of its proper divisors (1595127888).

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

665218512 is a wasteful number, since it uses less digits than its factorization.

665218512 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4150 (or 4134 counting only the distinct ones).

The product of its digits is 28800, while the sum is 36.

The square root of 665218512 is about 25791.8303344295. The cubic root of 665218512 is about 872.9474663617.

The spelling of 665218512 in words is "six hundred sixty-five million, two hundred eighteen thousand, five hundred twelve".