66546555561 has 24 divisors (see below), whose sum is σ = 101050779680. Its totient is φ = 43282283040.

The previous prime is 66546555553. The next prime is 66546555571. The reversal of 66546555561 is 16555564566.

It is not a de Polignac number, because 66546555561 - 2³ = 66546555553 is a prime.

It is a super-4 number, since 4×66546555561⁴ (a number of 44 digits) contains 4444 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 66546555498 and 66546555507.

It is not an unprimeable number, because it can be changed into a prime (66546555571) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 687715 + ... + 778488.

Almost surely, 2^66546555561 is an apocalyptic number.

It is an amenable number.

66546555561 is a deficient number, since it is larger than the sum of its proper divisors (34504224119).

66546555561 is a wasteful number, since it uses less digits than its factorization.

66546555561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1466294 (or 1466247 counting only the distinct ones).

The product of its digits is 16200000, while the sum is 54.

The spelling of 66546555561 in words is "sixty-six billion, five hundred forty-six million, five hundred fifty-five thousand, five hundred sixty-one".