818225991 has 12 divisors (see below), whose sum is σ = 1289325960. Its totient is φ = 495894480.

The previous prime is 818225987. The next prime is 818225999. The reversal of 818225991 is 199522818.

It is not a de Polignac number, because 818225991 - 2² = 818225987 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (818225999) 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 11 ways as a sum of consecutive naturals, for example, 4132356 + ... + 4132553.

It is an arithmetic number, because the mean of its divisors is an integer number (107443830).

Almost surely, 2^818225991 is an apocalyptic number.

818225991 is a deficient number, since it is larger than the sum of its proper divisors (471099969).

818225991 is a wasteful number, since it uses less digits than its factorization.

818225991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8264926 (or 8264923 counting only the distinct ones).

The product of its digits is 103680, while the sum is 45.

The square root of 818225991 is about 28604.6498143221. The cubic root of 818225991 is about 935.3146932748.

The spelling of 818225991 in words is "eight hundred eighteen million, two hundred twenty-five thousand, nine hundred ninety-one".