665542656 has 280 divisors, whose sum is σ = 2140930440. Its totient is φ = 205258752.

The previous prime is 665542649. The next prime is 665542681. The reversal of 665542656 is 656245566.

It is a happy number.

Its product of digits (1296000) is a multiple of the sum of its prime divisors (81).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 11280355 + ... + 11280413.

Almost surely, 2^665542656 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 665542656, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1070465220).

665542656 is an abundant number, since it is smaller than the sum of its proper divisors (1475387784).

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

665542656 is an equidigital number, since it uses as much as digits as its factorization.

665542656 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 114 (or 81 counting only the distinct ones).

The product of its digits is 1296000, while the sum is 45.

The square root of 665542656 is about 25798.1134193956. The cubic root of 665542656 is about 873.0892316769.

The spelling of 665542656 in words is "six hundred sixty-five million, five hundred forty-two thousand, six hundred fifty-six".