999988217 has 2 divisors, whose sum is σ = 999988218. Its totient is φ = 999988216.

The previous prime is 999988201. The next prime is 999988219. The reversal of 999988217 is 712889999.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 623201296 + 376786921 = 24964^2 + 19411^2 .

It is a cyclic number.

It is not a de Polignac number, because 999988217 - 2⁴ = 999988201 is a prime.

Together with 999988219, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 999988217.

It is not a weakly prime, because it can be changed into another prime (999988219) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 499994108 + 499994109.

It is an arithmetic number, because the mean of its divisors is an integer number (499994109).

Almost surely, 2^999988217 is an apocalyptic number.

It is an amenable number.

999988217 is a deficient number, since it is larger than the sum of its proper divisors (1).

999988217 is an equidigital number, since it uses as much as digits as its factorization.

999988217 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5878656, while the sum is 62.

The square root of 999988217 is about 31622.5902955466. The cubic root of 999988217 is about 999.9960723179.

The spelling of 999988217 in words is "nine hundred ninety-nine million, nine hundred eighty-eight thousand, two hundred seventeen".