991982605 has 4 divisors (see below), whose sum is σ = 1190379132. Its totient is φ = 793586080.

The previous prime is 991982603. The next prime is 991982633. The reversal of 991982605 is 506289199.

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 548543241 + 443439364 = 23421^2 + 21058^2 .

It is not a de Polignac number, because 991982605 - 2¹ = 991982603 is a prime.

It is a Smith number, since the sum of its digits (49) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (991982603) 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, 99198256 + ... + 99198265.

It is an arithmetic number, because the mean of its divisors is an integer number (297594783).

Almost surely, 2^991982605 is an apocalyptic number.

It is an amenable number.

991982605 is a deficient number, since it is larger than the sum of its proper divisors (198396527).

991982605 is a wasteful number, since it uses less digits than its factorization.

991982605 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 198396526.

The product of its (nonzero) digits is 349920, while the sum is 49.

The square root of 991982605 is about 31495.7553489355. The cubic root of 991982605 is about 997.3203609482.

The spelling of 991982605 in words is "nine hundred ninety-one million, nine hundred eighty-two thousand, six hundred five".