20912017054781 has 2 divisors, whose sum is σ = 20912017054782. Its totient is φ = 20912017054780.

The previous prime is 20912017054763. The next prime is 20912017054783. The reversal of 20912017054781 is 18745071021902.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20724882946681 + 187134108100 = 4552459^2 + 432590^2 .

It is a cyclic number.

It is not a de Polignac number, because 20912017054781 - 2³⁸ = 20637139147837 is a prime.

It is a super-2 number, since 2×20912017054781² (a number of 27 digits) contains 22 as substring.

Together with 20912017054783, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20912017054783) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10456008527390 + 10456008527391.

It is an arithmetic number, because the mean of its divisors is an integer number (10456008527391).

Almost surely, 2^{20912017054781} is an apocalyptic number.

It is an amenable number.

20912017054781 is a deficient number, since it is larger than the sum of its proper divisors (1).

20912017054781 is an equidigital number, since it uses as much as digits as its factorization.

20912017054781 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 282240, while the sum is 47.

The spelling of 20912017054781 in words is "twenty trillion, nine hundred twelve billion, seventeen million, fifty-four thousand, seven hundred eighty-one".