819998019809 has 4 divisors (see below), whose sum is σ = 820051133616. Its totient is φ = 819944906004.

The previous prime is 819998019793. The next prime is 819998019811. The reversal of 819998019809 is 908910899918.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 819998019809 - 2⁴ = 819998019793 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (819998016809) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 26533739 + ... + 26564624.

It is an arithmetic number, because the mean of its divisors is an integer number (205012783404).

Almost surely, 2^819998019809 is an apocalyptic number.

It is an amenable number.

819998019809 is a deficient number, since it is larger than the sum of its proper divisors (53113807).

819998019809 is a wasteful number, since it uses less digits than its factorization.

819998019809 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 53113806.

The product of its (nonzero) digits is 30233088, while the sum is 71.

The spelling of 819998019809 in words is "eight hundred nineteen billion, nine hundred ninety-eight million, nineteen thousand, eight hundred nine".