999986639 has 2 divisors, whose sum is σ = 999986640. Its totient is φ = 999986638.

The previous prime is 999986627. The next prime is 999986641. The reversal of 999986639 is 936689999.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-999986639 is a prime.

Together with 999986641, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (999986609) 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 as a sum of consecutive naturals, namely, 499993319 + 499993320.

It is an arithmetic number, because the mean of its divisors is an integer number (499993320).

Almost surely, 2^999986639 is an apocalyptic number.

999986639 is a deficient number, since it is larger than the sum of its proper divisors (1).

999986639 is an equidigital number, since it uses as much as digits as its factorization.

999986639 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 51018336, while the sum is 68.

The square root of 999986639 is about 31622.5653450191. The cubic root of 999986639 is about 999.9955463135.

The spelling of 999986639 in words is "nine hundred ninety-nine million, nine hundred eighty-six thousand, six hundred thirty-nine".