998591591 has 2 divisors, whose sum is σ = 998591592. Its totient is φ = 998591590.

The previous prime is 998591567. The next prime is 998591639. The reversal of 998591591 is 195195899.

It is a happy number.

It is a weak prime.

It is an emirp because it is prime and its reverse (195195899) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-998591591 is a prime.

It is a super-2 number, since 2×998591591² = 1994370331231822562, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (998591291) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 499295795 + 499295796.

It is an arithmetic number, because the mean of its divisors is an integer number (499295796).

Almost surely, 2^998591591 is an apocalyptic number.

998591591 is a deficient number, since it is larger than the sum of its proper divisors (1).

998591591 is an equidigital number, since it uses as much as digits as its factorization.

998591591 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1312200, while the sum is 56.

The square root of 998591591 is about 31600.4998536416. The cubic root of 998591591 is about 999.5303097590.

The spelling of 998591591 in words is "nine hundred ninety-eight million, five hundred ninety-one thousand, five hundred ninety-one".