990881 has 2 divisors, whose sum is σ = 990882. Its totient is φ = 990880.

The previous prime is 990851. The next prime is 990887. The reversal of 990881 is 188099.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 654481 + 336400 = 809^2 + 580^2 .

It is a cyclic number.

It is not a de Polignac number, because 990881 - 2¹⁴ = 974497 is a prime.

It is a super-2 number, since 2×990881² = 1963690312322, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (990887) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 495440 + 495441.

It is an arithmetic number, because the mean of its divisors is an integer number (495441).

2⁹⁹⁰⁸⁸¹ is an apocalyptic number.

It is an amenable number.

990881 is a deficient number, since it is larger than the sum of its proper divisors (1).

990881 is an equidigital number, since it uses as much as digits as its factorization.

990881 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 5184, while the sum is 35.

The square root of 990881 is about 995.4300578142. The cubic root of 990881 is about 99.6951046665.

The spelling of 990881 in words is "nine hundred ninety thousand, eight hundred eighty-one".