990331 has 2 divisors, whose sum is σ = 990332. Its totient is φ = 990330.

The previous prime is 990329. The next prime is 990349. The reversal of 990331 is 133099.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 990331 - 2¹ = 990329 is a prime.

It is a super-2 number, since 2×990331² = 1961510979122, which contains 22 as substring.

Together with 990329, it forms a pair of twin primes.

990331 is a lucky number.

It is a junction number, because it is equal to n+sod(n) for n = 990296 and 990305.

It is not a weakly prime, because it can be changed into another prime (990361) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 495165 + 495166.

It is an arithmetic number, because the mean of its divisors is an integer number (495166).

2⁹⁹⁰³³¹ is an apocalyptic number.

990331 is a deficient number, since it is larger than the sum of its proper divisors (1).

990331 is an equidigital number, since it uses as much as digits as its factorization.

990331 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 729, while the sum is 25.

The square root of 990331 is about 995.1537569642. The cubic root of 990331 is about 99.6766556109.

The spelling of 990331 in words is "nine hundred ninety thousand, three hundred thirty-one".