61661666011561 has 32 divisors (see below), whose sum is σ = 78691278302208. Its totient is φ = 46914808530240.

The previous prime is 61661666011559. The next prime is 61661666011609. The reversal of 61661666011561 is 16511066616616.

61661666011561 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 61661666011561 - 2¹ = 61661666011559 is a prime.

It is a super-2 number, since 2×61661666011561² (a number of 28 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 61661666011499 and 61661666011508.

It is not an unprimeable number, because it can be changed into a prime (61661666014561) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 6667855 + ... + 12953131.

It is an arithmetic number, because the mean of its divisors is an integer number (2459102446944).

Almost surely, 2^{61661666011561} is an apocalyptic number.

It is an amenable number.

61661666011561 is a deficient number, since it is larger than the sum of its proper divisors (17029612290647).

61661666011561 is a wasteful number, since it uses less digits than its factorization.

61661666011561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6288301.

The product of its (nonzero) digits is 1399680, while the sum is 52.

The spelling of 61661666011561 in words is "sixty-one trillion, six hundred sixty-one billion, six hundred sixty-six million, eleven thousand, five hundred sixty-one".