660561000521 has 4 divisors (see below), whose sum is σ = 671389869444. Its totient is φ = 649732131600.

The previous prime is 660561000503. The next prime is 660561000527. The reversal of 660561000521 is 125000165066.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 56266212025 + 604294788496 = 237205^2 + 777364^2 .

It is a cyclic number.

It is not a de Polignac number, because 660561000521 - 2¹⁸ = 660560738377 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (660561000527) 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 3 ways as a sum of consecutive naturals, for example, 5414434370 + ... + 5414434491.

It is an arithmetic number, because the mean of its divisors is an integer number (167847467361).

Almost surely, 2^660561000521 is an apocalyptic number.

660561000521 is a gapful number since it is divisible by the number (61) formed by its first and last digit.

It is an amenable number.

660561000521 is a deficient number, since it is larger than the sum of its proper divisors (10828868923).

660561000521 is a wasteful number, since it uses less digits than its factorization.

660561000521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10828868922.

The product of its (nonzero) digits is 10800, while the sum is 32.

Adding to 660561000521 its reverse (125000165066), we get a palindrome (785561165587).

The spelling of 660561000521 in words is "six hundred sixty billion, five hundred sixty-one million, five hundred twenty-one", and thus it is an aban number.