665671212 has 36 divisors (see below), whose sum is σ = 1683767176. Its totient is φ = 221745600.

The previous prime is 665671211. The next prime is 665671219. The reversal of 665671212 is 212176566.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (36).

It is a Smith number, since the sum of its digits (36) coincides with the sum of the digits of its prime factors.

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

It is not an unprimeable number, because it can be changed into a prime (665671211) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 59703 + ... + 69969.

Almost surely, 2^665671212 is an apocalyptic number.

It is an amenable number.

665671212 is an abundant number, since it is smaller than the sum of its proper divisors (1018095964).

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

665671212 is a wasteful number, since it uses less digits than its factorization.

665671212 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12078 (or 12073 counting only the distinct ones).

The product of its digits is 30240, while the sum is 36.

The square root of 665671212 is about 25800.6048766303. The cubic root of 665671212 is about 873.1454432672.

The spelling of 665671212 in words is "six hundred sixty-five million, six hundred seventy-one thousand, two hundred twelve".