20555385217 has 4 divisors (see below), whose sum is σ = 20555697456. Its totient is φ = 20555072980.

The previous prime is 20555385199. The next prime is 20555385247. The reversal of 20555385217 is 71258355502.

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: 71258355502 = 2 ⋅35629177751.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20555385217 is a prime.

It is a super-2 number, since 2×20555385217² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20555385247) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 14623 + ... + 203284.

It is an arithmetic number, because the mean of its divisors is an integer number (5138924364).

Almost surely, 2^20555385217 is an apocalyptic number.

It is an amenable number.

20555385217 is a deficient number, since it is larger than the sum of its proper divisors (312239).

20555385217 is an equidigital number, since it uses as much as digits as its factorization.

20555385217 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 312238.

The product of its (nonzero) digits is 420000, while the sum is 43.

The spelling of 20555385217 in words is "twenty billion, five hundred fifty-five million, three hundred eighty-five thousand, two hundred seventeen".