665398656 has 192 divisors, whose sum is σ = 2082509520. Its totient is φ = 202715136.

The previous prime is 665398651. The next prime is 665398661. The reversal of 665398656 is 656893566.

It is an interprime number because it is at equal distance from previous prime (665398651) and next prime (665398661).

It is a tau number, because it is divible by the number of its divisors (192).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (665398651) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2351091 + ... + 2351373.

Almost surely, 2^665398656 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 665398656, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1041254760).

665398656 is an abundant number, since it is smaller than the sum of its proper divisors (1417110864).

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

665398656 is a wasteful number, since it uses less digits than its factorization.

665398656 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 473 (or 458 counting only the distinct ones).

The product of its digits is 6998400, while the sum is 54.

The square root of 665398656 is about 25795.3223666618. The cubic root of 665398656 is about 873.0262585442.

The spelling of 665398656 in words is "six hundred sixty-five million, three hundred ninety-eight thousand, six hundred fifty-six".