991808199 has 16 divisors (see below), whose sum is σ = 1509059040. Its totient is φ = 643334400.

The previous prime is 991808197. The next prime is 991808249.

991808199 is nontrivially palindromic in base 10.

It is not a de Polignac number, because 991808199 - 2¹ = 991808197 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (991808197) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 495402 + ... + 497399.

It is an arithmetic number, because the mean of its divisors is an integer number (94316190).

Almost surely, 2^991808199 is an apocalyptic number.

991808199 is a deficient number, since it is larger than the sum of its proper divisors (517250841).

991808199 is a wasteful number, since it uses less digits than its factorization.

991808199 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 992847 (or 992841 counting only the distinct ones).

The product of its (nonzero) digits is 419904, while the sum is 54.

The square root of 991808199 is about 31492.9865049347. The cubic root of 991808199 is about 997.2619093690.

The spelling of 991808199 in words is "nine hundred ninety-one million, eight hundred eight thousand, one hundred ninety-nine".