20691842009 has 8 divisors (see below), whose sum is σ = 21920740200. Its totient is φ = 19464247296.

The previous prime is 20691841957. The next prime is 20691842051. The reversal of 20691842009 is 90024819602.

It can be written as a sum of positive squares in 4 ways, for example, as 1966656409 + 18725185600 = 44347^2 + 136840^2 .

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 20691842009 - 2³² = 16396874713 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20691842069) 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, 293084 + ... + 356765.

It is an arithmetic number, because the mean of its divisors is an integer number (2740092525).

Almost surely, 2^20691842009 is an apocalyptic number.

It is an amenable number.

20691842009 is a deficient number, since it is larger than the sum of its proper divisors (1228898191).

20691842009 is a wasteful number, since it uses less digits than its factorization.

20691842009 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 651739.

The product of its (nonzero) digits is 62208, while the sum is 41.

The spelling of 20691842009 in words is "twenty billion, six hundred ninety-one million, eight hundred forty-two thousand, nine".