661065561611 has 16 divisors (see below), whose sum is σ = 813769571328. Its totient is φ = 522944186400.

The previous prime is 661065561601. The next prime is 661065561613. The reversal of 661065561611 is 116165560166.

It is a cyclic number.

It is not a de Polignac number, because 661065561611 - 2³⁴ = 643885692427 is a prime.

It is a super-3 number, since 3×661065561611³ (a number of 36 digits) contains 333 as substring.

It is not an unprimeable number, because it can be changed into a prime (661065561613) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 174575 + ... + 1163016.

It is an arithmetic number, because the mean of its divisors is an integer number (50860598208).

Almost surely, 2^661065561611 is an apocalyptic number.

661065561611 is a deficient number, since it is larger than the sum of its proper divisors (152704009717).

661065561611 is a wasteful number, since it uses less digits than its factorization.

661065561611 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1343042.

The product of its (nonzero) digits is 194400, while the sum is 44.

The spelling of 661065561611 in words is "six hundred sixty-one billion, sixty-five million, five hundred sixty-one thousand, six hundred eleven".