665656416 has 72 divisors (see below), whose sum is σ = 1910740104. Its totient is φ = 219801600.

The previous prime is 665656399. The next prime is 665656423. The reversal of 665656416 is 614656566.

It is a tau number, because it is divible by the number of its divisors (72).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 20016 + ... + 41616.

It is an arithmetic number, because the mean of its divisors is an integer number (26538057).

Almost surely, 2^665656416 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 665656416, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (955370052).

665656416 is an abundant number, since it is smaller than the sum of its proper divisors (1245083688).

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

665656416 is a wasteful number, since it uses less digits than its factorization.

665656416 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21724 (or 21713 counting only the distinct ones).

The product of its digits is 777600, while the sum is 45.

The square root of 665656416 is about 25800.3181375734. The cubic root of 665656416 is about 873.1389740296.

The spelling of 665656416 in words is "six hundred sixty-five million, six hundred fifty-six thousand, four hundred sixteen".