66869561 has 12 divisors (see below), whose sum is σ = 74014500. Its totient is φ = 60366240.

The previous prime is 66869549. The next prime is 66869581. The reversal of 66869561 is 16596866.

It can be written as a sum of positive squares in 2 ways, for example, as 12390400 + 54479161 = 3520^2 + 7381^2 .

It is not a de Polignac number, because 66869561 - 2¹⁰ = 66868537 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66869581) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 16175 + ... + 19883.

It is an arithmetic number, because the mean of its divisors is an integer number (6167875).

Almost surely, 2^66869561 is an apocalyptic number.

It is an amenable number.

66869561 is a deficient number, since it is larger than the sum of its proper divisors (7144939).

66869561 is a wasteful number, since it uses less digits than its factorization.

66869561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3880 (or 3869 counting only the distinct ones).

The product of its digits is 466560, while the sum is 47.

The square root of 66869561 is about 8177.3810599727. The cubic root of 66869561 is about 405.8910645477.

The spelling of 66869561 in words is "sixty-six million, eight hundred sixty-nine thousand, five hundred sixty-one".