660534021 has 48 divisors (see below), whose sum is σ = 1134433664. Its totient is φ = 376233984.

The previous prime is 660533999. The next prime is 660534103. The reversal of 660534021 is 120435066.

660534021 is a `hidden beast` number, since 6 + 605 + 34 + 0 + 21 = 666.

It is not a de Polignac number, because 660534021 - 2⁵ = 660533989 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (660534821) 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 47 ways as a sum of consecutive naturals, for example, 981141 + ... + 981813.

Almost surely, 2^660534021 is an apocalyptic number.

It is an amenable number.

660534021 is a deficient number, since it is larger than the sum of its proper divisors (473899643).

660534021 is an equidigital number, since it uses as much as digits as its factorization.

660534021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1272 (or 1260 counting only the distinct ones).

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

The square root of 660534021 is about 25700.8564254190. The cubic root of 660534021 is about 870.8935290781.

Adding to 660534021 its reverse (120435066), we get a palindrome (780969087).

The spelling of 660534021 in words is "six hundred sixty million, five hundred thirty-four thousand, twenty-one".