663655680 has 360 divisors, whose sum is σ = 2452959432. Its totient is φ = 171196416.

The previous prime is 663655649. The next prime is 663655697. The reversal of 663655680 is 86556366.

663655680 is a `hidden beast` number, since 6 + 636 + 5 + 5 + 6 + 8 + 0 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 334450944 + 329204736 = 18288^2 + 18144^2 .

It is a tau number, because it is divible by the number of its divisors (360).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 3836074 + ... + 3836246.

Almost surely, 2^663655680 is an apocalyptic number.

663655680 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 663655680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1226479716).

663655680 is an abundant number, since it is smaller than the sum of its proper divisors (1789303752).

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

663655680 is a wasteful number, since it uses less digits than its factorization.

663655680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 243 (or 220 counting only the distinct ones).

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

The square root of 663655680 is about 25761.5154833717. The cubic root of 663655680 is about 872.2633102084.

The spelling of 663655680 in words is "six hundred sixty-three million, six hundred fifty-five thousand, six hundred eighty".