819121919 has 16 divisors (see below), whose sum is σ = 1023321600. Its totient is φ = 636977760.

The previous prime is 819121883. The next prime is 819121949. The reversal of 819121919 is 919121918.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-819121919 is a prime.

It is a super-2 number, since 2×819121919² = 1341921436372485122, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (819121949) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 28157 + ... + 49305.

It is an arithmetic number, because the mean of its divisors is an integer number (63957600).

Almost surely, 2^819121919 is an apocalyptic number.

819121919 is a deficient number, since it is larger than the sum of its proper divisors (204199681).

819121919 is a wasteful number, since it uses less digits than its factorization.

819121919 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21670.

The product of its digits is 11664, while the sum is 41.

The square root of 819121919 is about 28620.3060605578. The cubic root of 819121919 is about 935.6559473892.

Subtracting 819121919 from its reverse (919121918), we obtain a palindrome (99999999).

The spelling of 819121919 in words is "eight hundred nineteen million, one hundred twenty-one thousand, nine hundred nineteen".