990631 has 2 divisors, whose sum is σ = 990632. Its totient is φ = 990630.

The previous prime is 990599. The next prime is 990637. The reversal of 990631 is 136099.

It is a happy number.

It is a strong prime.

It is an emirp because it is prime and its reverse (136099) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 990631 - 2⁵ = 990599 is a prime.

It is a super-2 number, since 2×990631² = 1962699556322, which contains 22 as substring.

It is equal to p₇₇₈₂₄ and since 990631 and 77824 have the same sum of digits, it is a Honaker prime.

It is a self number, because there is not a number n which added to its sum of digits gives 990631.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (990637) 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, 495315 + 495316.

It is an arithmetic number, because the mean of its divisors is an integer number (495316).

2⁹⁹⁰⁶³¹ is an apocalyptic number.

990631 is a deficient number, since it is larger than the sum of its proper divisors (1).

990631 is an equidigital number, since it uses as much as digits as its factorization.

990631 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1458, while the sum is 28.

The square root of 990631 is about 995.3044760273. The cubic root of 990631 is about 99.6867195787.

The spelling of 990631 in words is "nine hundred ninety thousand, six hundred thirty-one".