20591967917 has 4 divisors (see below), whose sum is σ = 20840064000. Its totient is φ = 20343871836.

The previous prime is 20591967863. The next prime is 20591967943. The reversal of 20591967917 is 71976919502.

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 20591967917 - 2⁸ = 20591967661 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20591967017) 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 3 ways as a sum of consecutive naturals, for example, 124047917 + ... + 124048082.

It is an arithmetic number, because the mean of its divisors is an integer number (5210016000).

Almost surely, 2^20591967917 is an apocalyptic number.

It is an amenable number.

20591967917 is a deficient number, since it is larger than the sum of its proper divisors (248096083).

20591967917 is an equidigital number, since it uses as much as digits as its factorization.

20591967917 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 248096082.

The product of its (nonzero) digits is 2143260, while the sum is 56.

The spelling of 20591967917 in words is "twenty billion, five hundred ninety-one million, nine hundred sixty-seven thousand, nine hundred seventeen".