660778560 has 560 divisors, whose sum is σ = 2648779056. Its totient is φ = 155271168.

The previous prime is 660778529. The next prime is 660778571. The reversal of 660778560 is 65877066.

It can be written as a sum of positive squares in 8 ways, for example, as 3779136 + 656999424 = 1944^2 + 25632^2 .

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

It is an unprimeable number.

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 79 ways as a sum of consecutive naturals, for example, 12467494 + ... + 12467546.

Almost surely, 2^660778560 is an apocalyptic number.

660778560 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 660778560, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1324389528).

660778560 is an abundant number, since it is smaller than the sum of its proper divisors (1988000496).

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

660778560 is a wasteful number, since it uses less digits than its factorization.

660778560 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 132 (or 113 counting only the distinct ones).

The product of its (nonzero) digits is 423360, while the sum is 45.

The square root of 660778560 is about 25705.6133947432. The cubic root of 660778560 is about 871.0009881694. Note that the first 3 decimals are identical.

The spelling of 660778560 in words is "six hundred sixty million, seven hundred seventy-eight thousand, five hundred sixty".