21355401912917 has 2 divisors, whose sum is σ = 21355401912918. Its totient is φ = 21355401912916.

The previous prime is 21355401912893. The next prime is 21355401912953. The reversal of 21355401912917 is 71921910455312.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13530229295716 + 7825172617201 = 3678346^2 + 2797351^2 .

It is a cyclic number.

It is not a de Polignac number, because 21355401912917 - 2¹⁴ = 21355401896533 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21355401912967) 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 as a sum of consecutive naturals, namely, 10677700956458 + 10677700956459.

It is an arithmetic number, because the mean of its divisors is an integer number (10677700956459).

Almost surely, 2^{21355401912917} is an apocalyptic number.

It is an amenable number.

21355401912917 is a deficient number, since it is larger than the sum of its proper divisors (1).

21355401912917 is an equidigital number, since it uses as much as digits as its factorization.

21355401912917 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 680400, while the sum is 50.

The spelling of 21355401912917 in words is "twenty-one trillion, three hundred fifty-five billion, four hundred one million, nine hundred twelve thousand, nine hundred seventeen".