866651115509 has 16 divisors (see below), whose sum is σ = 907436113920. Its totient is φ = 826127467440.

The previous prime is 866651115503. The next prime is 866651115541. The reversal of 866651115509 is 905511156668.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 866651115509 - 2²⁴ = 866634338293 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (866651115503) 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 15 ways as a sum of consecutive naturals, for example, 14967404 + ... + 15025194.

It is an arithmetic number, because the mean of its divisors is an integer number (56714757120).

Almost surely, 2^866651115509 is an apocalyptic number.

It is an amenable number.

866651115509 is a deficient number, since it is larger than the sum of its proper divisors (40784998411).

866651115509 is a wasteful number, since it uses less digits than its factorization.

866651115509 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 60040.

The product of its (nonzero) digits is 1944000, while the sum is 53.

The spelling of 866651115509 in words is "eight hundred sixty-six billion, six hundred fifty-one million, one hundred fifteen thousand, five hundred nine".