999999998531 has 2 divisors, whose sum is σ = 999999998532. Its totient is φ = 999999998530.

The previous prime is 999999998527. The next prime is 999999998533. The reversal of 999999998531 is 135899999999.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 999999998531 - 2² = 999999998527 is a prime.

It is a super-2 number, since 2×999999998531² (a number of 25 digits) contains 22 as substring.

Together with 999999998533, it forms a pair of twin primes.

It is a Chen prime.

It is a nialpdrome in base 10.

It is not a weakly prime, because it can be changed into another prime (999999998533) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 499999999265 + 499999999266.

It is an arithmetic number, because the mean of its divisors is an integer number (499999999266).

Almost surely, 2^999999998531 is an apocalyptic number.

999999998531 is a deficient number, since it is larger than the sum of its proper divisors (1).

999999998531 is an equidigital number, since it uses as much as digits as its factorization.

999999998531 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5165606520, while the sum is 89.

The spelling of 999999998531 in words is "nine hundred ninety-nine billion, nine hundred ninety-nine million, nine hundred ninety-eight thousand, five hundred thirty-one".