20556216959 has 2 divisors, whose sum is σ = 20556216960. Its totient is φ = 20556216958.

The previous prime is 20556216953. The next prime is 20556216973. The reversal of 20556216959 is 95961265502.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20556216959 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20556216953) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10278108479 + 10278108480.

It is an arithmetic number, because the mean of its divisors is an integer number (10278108480).

Almost surely, 2^20556216959 is an apocalyptic number.

20556216959 is a deficient number, since it is larger than the sum of its proper divisors (1).

20556216959 is an equidigital number, since it uses as much as digits as its factorization.

20556216959 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1458000, while the sum is 50.

The spelling of 20556216959 in words is "twenty billion, five hundred fifty-six million, two hundred sixteen thousand, nine hundred fifty-nine".