660643566 has 32 divisors (see below), whose sum is σ = 1517270400. Its totient is φ = 189658080.

The previous prime is 660643553. The next prime is 660643567. The reversal of 660643566 is 665346066.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (660643567) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 262161 + ... + 264668.

It is an arithmetic number, because the mean of its divisors is an integer number (47414700).

Almost surely, 2^660643566 is an apocalyptic number.

660643566 is a gapful number since it is divisible by the number (66) formed by its first and last digit.

660643566 is an abundant number, since it is smaller than the sum of its proper divisors (856626834).

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

660643566 is a wasteful number, since it uses less digits than its factorization.

660643566 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 526864.

The product of its (nonzero) digits is 466560, while the sum is 42.

The square root of 660643566 is about 25702.9874917294. The cubic root of 660643566 is about 870.9416703069.

The spelling of 660643566 in words is "six hundred sixty million, six hundred forty-three thousand, five hundred sixty-six".