999999986666678 has 4 divisors (see below), whose sum is σ = 1499999980000020. Its totient is φ = 499999993333338.

The previous prime is 999999986666677. The next prime is 999999986666741. The reversal of 999999986666678 is 876666689999999.

It is a semiprime because it is the product of two primes.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (999999986666677) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 249999996666668 + ... + 249999996666671.

It is an arithmetic number, because the mean of its divisors is an integer number (374999995000005).

Almost surely, 2^{999999986666678} is an apocalyptic number.

999999986666678 is a deficient number, since it is larger than the sum of its proper divisors (499999993333342).

999999986666678 is a wasteful number, since it uses less digits than its factorization.

999999986666678 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 499999993333341.

The product of its digits is 16662180390912, while the sum is 116.

The spelling of 999999986666678 in words is "nine hundred ninety-nine trillion, nine hundred ninety-nine billion, nine hundred eighty-six million, six hundred sixty-six thousand, six hundred seventy-eight".