665212056 has 64 divisors (see below), whose sum is σ = 1706158080. Its totient is φ = 216030720.

The previous prime is 665212039. The next prime is 665212061. The reversal of 665212056 is 650212566.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 270625 + ... + 273071.

It is an arithmetic number, because the mean of its divisors is an integer number (26658720).

Almost surely, 2^665212056 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 665212056, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (853079040).

665212056 is an abundant number, since it is smaller than the sum of its proper divisors (1040946024).

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

665212056 is a wasteful number, since it uses less digits than its factorization.

665212056 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2744 (or 2740 counting only the distinct ones).

The product of its (nonzero) digits is 21600, while the sum is 33.

The square root of 665212056 is about 25791.7051782157. The cubic root of 665212056 is about 872.9446423437.

The spelling of 665212056 in words is "six hundred sixty-five million, two hundred twelve thousand, fifty-six".