61666687405 has 8 divisors (see below), whose sum is σ = 74120746392. Its totient is φ = 49252868928.

The previous prime is 61666687363. The next prime is 61666687531. The reversal of 61666687405 is 50478666616.

It can be written as a sum of positive squares in 4 ways, for example, as 10403388009 + 51263299396 = 101997^2 + 226414^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 61666687405 - 2²³ = 61658298797 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 10056754 + ... + 10062883.

It is an arithmetic number, because the mean of its divisors is an integer number (9265093299).

Almost surely, 2^61666687405 is an apocalyptic number.

It is an amenable number.

61666687405 is a deficient number, since it is larger than the sum of its proper divisors (12454058987).

61666687405 is a wasteful number, since it uses less digits than its factorization.

61666687405 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20120255.

The product of its (nonzero) digits is 8709120, while the sum is 55.

The spelling of 61666687405 in words is "sixty-one billion, six hundred sixty-six million, six hundred eighty-seven thousand, four hundred five".