61661133561 has 16 divisors (see below), whose sum is σ = 86577940800. Its totient is φ = 38927674368.

The previous prime is 61661133553. The next prime is 61661133563. The reversal of 61661133561 is 16533116616.

It is not a de Polignac number, because 61661133561 - 2³ = 61661133553 is a prime.

It is not an unprimeable number, because it can be changed into a prime (61661133563) 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, 86016 + ... + 361553.

It is an arithmetic number, because the mean of its divisors is an integer number (5411121300).

Almost surely, 2^61661133561 is an apocalyptic number.

It is an amenable number.

61661133561 is a deficient number, since it is larger than the sum of its proper divisors (24916807239).

61661133561 is a wasteful number, since it uses less digits than its factorization.

61661133561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 450008.

The product of its digits is 58320, while the sum is 39.

The spelling of 61661133561 in words is "sixty-one billion, six hundred sixty-one million, one hundred thirty-three thousand, five hundred sixty-one".