849999991 has 8 divisors (see below), whose sum is σ = 854128368. Its totient is φ = 845880000.

The previous prime is 849999977. The next prime is 850000013. The reversal of 849999991 is 199999948.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 849999991 - 2⁵ = 849999959 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (849999971) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 296716 + ... + 299566.

It is an arithmetic number, because the mean of its divisors is an integer number (106766046).

Almost surely, 2^849999991 is an apocalyptic number.

849999991 is a deficient number, since it is larger than the sum of its proper divisors (4128377).

849999991 is a wasteful number, since it uses less digits than its factorization.

849999991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4193.

The product of its digits is 17006112, while the sum is 67.

The square root of 849999991 is about 29154.7593198778. The cubic root of 849999991 is about 947.2682338426.

Adding to 849999991 its sum of digits (67), we get a palindrome (850000058).

The spelling of 849999991 in words is "eight hundred forty-nine million, nine hundred ninety-nine thousand, nine hundred ninety-one".