660611561 has 16 divisors (see below), whose sum is σ = 691770240. Its totient is φ = 630067200.

The previous prime is 660611533. The next prime is 660611563. The reversal of 660611561 is 165116066.

It is a cyclic number.

It is not a de Polignac number, because 660611561 - 2¹⁰ = 660610537 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (660611563) by changing a digit.

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 15 ways as a sum of consecutive naturals, for example, 1125110 + ... + 1125696.

It is an arithmetic number, because the mean of its divisors is an integer number (43235640).

Almost surely, 2^660611561 is an apocalyptic number.

It is an amenable number.

660611561 is a deficient number, since it is larger than the sum of its proper divisors (31158679).

660611561 is a wasteful number, since it uses less digits than its factorization.

660611561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1024.

The product of its (nonzero) digits is 6480, while the sum is 32.

The square root of 660611561 is about 25702.3648911924. The cubic root of 660611561 is about 870.9276057695.

The spelling of 660611561 in words is "six hundred sixty million, six hundred eleven thousand, five hundred sixty-one".