991990104169 has 3 divisors (see below), whose sum is σ = 991991100157. Its totient is φ = 991989108182.

The previous prime is 991990104073. The next prime is 991990104179. The reversal of 991990104169 is 961401099199.

The square root of 991990104169 is 995987.

It is a perfect power (a square), and thus also a powerful number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is not a de Polignac number, because 991990104169 - 2¹¹ = 991990102121 is a prime.

It is a super-2 number, since 2×991990104169² (a number of 25 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (991990104179) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 497994 + ... + 1493980.

Almost surely, 2^991990104169 is an apocalyptic number.

991990104169 is the 995987-th square number.

991990104169 is the 497994-th centered octagonal number.

It is an amenable number.

991990104169 is a deficient number, since it is larger than the sum of its proper divisors (995988).

991990104169 is an frugal number, since it uses more digits than its factorization.

991990104169 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1991974 (or 995987 counting only the distinct ones).

The product of its (nonzero) digits is 1417176, while the sum is 58.

The spelling of 991990104169 in words is "nine hundred ninety-one billion, nine hundred ninety million, one hundred four thousand, one hundred sixty-nine".