660561 has 16 divisors (see below), whose sum is σ = 988608. Its totient is φ = 388800.

The previous prime is 660559. The next prime is 660563. The reversal of 660561 is 165066.

It is an interprime number because it is at equal distance from previous prime (660559) and next prime (660563).

It is not a de Polignac number, because 660561 - 2¹ = 660559 is a prime.

It is not an unprimeable number, because it can be changed into a prime (660563) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 951 + ... + 1491.

It is an arithmetic number, because the mean of its divisors is an integer number (61788).

2⁶⁶⁰⁵⁶¹ is an apocalyptic number.

It is an amenable number.

660561 is a deficient number, since it is larger than the sum of its proper divisors (328047).

660561 is a wasteful number, since it uses less digits than its factorization.

660561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 592.

The product of its (nonzero) digits is 1080, while the sum is 24.

The square root of 660561 is about 812.7490387567. The cubic root of 660561 is about 87.0905385907.

It can be divided in two parts, 6605 and 61, that added together give a palindrome (6666).

The spelling of 660561 in words is "six hundred sixty thousand, five hundred sixty-one".