661887208673 has 8 divisors (see below), whose sum is σ = 665939515560. Its totient is φ = 657845694720.

The previous prime is 661887208657. The next prime is 661887208699. The reversal of 661887208673 is 376802788166.

It can be written as a sum of positive squares in 4 ways, for example, as 485875914304 + 176011294369 = 697048^2 + 419537^2 .

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 661887208673 - 2⁴ = 661887208657 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (661887208603) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2575190 + ... + 2820527.

It is an arithmetic number, because the mean of its divisors is an integer number (83242439445).

Almost surely, 2^661887208673 is an apocalyptic number.

It is an amenable number.

661887208673 is a deficient number, since it is larger than the sum of its proper divisors (4052306887).

661887208673 is a wasteful number, since it uses less digits than its factorization.

661887208673 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5396467.

The product of its (nonzero) digits is 32514048, while the sum is 62.

The spelling of 661887208673 in words is "six hundred sixty-one billion, eight hundred eighty-seven million, two hundred eight thousand, six hundred seventy-three".