21317580762481 has 2 divisors, whose sum is σ = 21317580762482. Its totient is φ = 21317580762480.

The previous prime is 21317580762463. The next prime is 21317580762557. The reversal of 21317580762481 is 18426708571312.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16673624722225 + 4643956040256 = 4083335^2 + 2154984^2 .

It is a cyclic number.

It is not a de Polignac number, because 21317580762481 - 2⁴¹ = 19118557506929 is a prime.

It is a super-2 number, since 2×21317580762481² (a number of 27 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21317580762581) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10658790381240 + 10658790381241.

It is an arithmetic number, because the mean of its divisors is an integer number (10658790381241).

Almost surely, 2^{21317580762481} is an apocalyptic number.

It is an amenable number.

21317580762481 is a deficient number, since it is larger than the sum of its proper divisors (1).

21317580762481 is an equidigital number, since it uses as much as digits as its factorization.

21317580762481 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4515840, while the sum is 55.

The spelling of 21317580762481 in words is "twenty-one trillion, three hundred seventeen billion, five hundred eighty million, seven hundred sixty-two thousand, four hundred eighty-one".