990871985 has 4 divisors (see below), whose sum is σ = 1189046388. Its totient is φ = 792697584.

The previous prime is 990871961. The next prime is 990872023. The reversal of 990871985 is 589178099.

It is a happy number.

990871985 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 251412736 + 739459249 = 15856^2 + 27193^2 .

It is a cyclic number.

It is not a de Polignac number, because 990871985 - 2¹⁰ = 990870961 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 990871985.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 99087194 + ... + 99087203.

It is an arithmetic number, because the mean of its divisors is an integer number (297261597).

Almost surely, 2^990871985 is an apocalyptic number.

It is an amenable number.

990871985 is a deficient number, since it is larger than the sum of its proper divisors (198174403).

990871985 is a wasteful number, since it uses less digits than its factorization.

990871985 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 198174402.

The product of its (nonzero) digits is 1632960, while the sum is 56.

The square root of 990871985 is about 31478.1191464801. The cubic root of 990871985 is about 996.9480232472.

The spelling of 990871985 in words is "nine hundred ninety million, eight hundred seventy-one thousand, nine hundred eighty-five".