191820202009 has 4 divisors (see below), whose sum is σ = 200160210816. Its totient is φ = 183480193204.

The previous prime is 191820201997. The next prime is 191820202019. The reversal of 191820202009 is 900202028191.

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, and also an emirpimes, since its reverse is a distinct semiprime: 900202028191 = 23 ⋅39139218617.

It is a cyclic number.

It is not a de Polignac number, because 191820202009 - 2⁵ = 191820201977 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (191820202019) 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, 4170004369 + ... + 4170004414.

It is an arithmetic number, because the mean of its divisors is an integer number (50040052704).

Almost surely, 2^191820202009 is an apocalyptic number.

It is an amenable number.

191820202009 is a deficient number, since it is larger than the sum of its proper divisors (8340008807).

191820202009 is an equidigital number, since it uses as much as digits as its factorization.

191820202009 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8340008806.

The product of its (nonzero) digits is 5184, while the sum is 34.

The spelling of 191820202009 in words is "one hundred ninety-one billion, eight hundred twenty million, two hundred two thousand, nine".