21711788554957 has 2 divisors, whose sum is σ = 21711788554958. Its totient is φ = 21711788554956.

The previous prime is 21711788554891. The next prime is 21711788555021. The reversal of 21711788554957 is 75945588711712.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21241166486596 + 470622068361 = 4608814^2 + 686019^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21711788554957 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21711788554457) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10855894277478 + 10855894277479.

It is an arithmetic number, because the mean of its divisors is an integer number (10855894277479).

Almost surely, 2^{21711788554957} is an apocalyptic number.

It is an amenable number.

21711788554957 is a deficient number, since it is larger than the sum of its proper divisors (1).

21711788554957 is an equidigital number, since it uses as much as digits as its factorization.

21711788554957 is an evil number, because the sum of its binary digits is even.

The product of its digits is 197568000, while the sum is 70.

The spelling of 21711788554957 in words is "twenty-one trillion, seven hundred eleven billion, seven hundred eighty-eight million, five hundred fifty-four thousand, nine hundred fifty-seven".