665640000 has 315 divisors, whose sum is σ = 2440892883. Its totient is φ = 173376000.

The previous prime is 665639993. The next prime is 665640013. The reversal of 665640000 is 46566.

The square root of 665640000 is 25800.

It is a perfect power (a square), and thus also a powerful number.

665640000 is a `hidden beast` number, since 6 + 656 + 4 + 0 + 0 + 0 + 0 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 52186176 + 613453824 = 7224^2 + 24768^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 44 ways as a sum of consecutive naturals, for example, 15479979 + ... + 15480021.

Almost surely, 2^665640000 is an apocalyptic number.

665640000 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

665640000 is the 25800-th square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 665640000

665640000 is an abundant number, since it is smaller than the sum of its proper divisors (1775252883).

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

665640000 is an equidigital number, since it uses as much as digits as its factorization.

665640000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 124 (or 53 counting only the distinct ones).

The product of its (nonzero) digits is 4320, while the sum is 27.

The cubic root of 665640000 is about 873.1317963691.

Adding to 665640000 its reverse (46566), we get a palindrome (665686566).

It can be divided in two parts, 6656 and 40000, that added together give a 6-th power (46656 = 6⁶).

The spelling of 665640000 in words is "six hundred sixty-five million, six hundred forty thousand".