991990996 has 12 divisors (see below), whose sum is σ = 1746020052. Its totient is φ = 493128128.

The previous prime is 991990981. The next prime is 991990997. The reversal of 991990996 is 699099199.

It can be written as a sum of positive squares in 2 ways, for example, as 832322500 + 159668496 = 28850^2 + 12636^2 .

It is a super-2 number, since 2×991990996² = 1968092272290144032, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (991990997) 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 in 3 ways as a sum of consecutive naturals, for example, 716065 + ... + 717448.

It is an arithmetic number, because the mean of its divisors is an integer number (145501671).

Almost surely, 2^991990996 is an apocalyptic number.

It is an amenable number.

991990996 is a deficient number, since it is larger than the sum of its proper divisors (754029056).

991990996 is a wasteful number, since it uses less digits than its factorization.

991990996 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1433690 (or 1433688 counting only the distinct ones).

The product of its (nonzero) digits is 3188646, while the sum is 61.

The square root of 991990996 is about 31495.8885570800. Note that the first 3 decimals coincide. The cubic root of 991990996 is about 997.3231729907.

The spelling of 991990996 in words is "nine hundred ninety-one million, nine hundred ninety thousand, nine hundred ninety-six".