21313121221081 has 2 divisors, whose sum is σ = 21313121221082. Its totient is φ = 21313121221080.

The previous prime is 21313121221043. The next prime is 21313121221099. The reversal of 21313121221081 is 18012212131312.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21313041726025 + 79495056 = 4616605^2 + 8916^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21313121221081 is a prime.

It is a super-2 number, since 2×21313121221081² (a number of 27 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21313121221681) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10656560610540 + 10656560610541.

It is an arithmetic number, because the mean of its divisors is an integer number (10656560610541).

Almost surely, 2^{21313121221081} is an apocalyptic number.

It is an amenable number.

21313121221081 is a deficient number, since it is larger than the sum of its proper divisors (1).

21313121221081 is an equidigital number, since it uses as much as digits as its factorization.

21313121221081 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1152, while the sum is 28.

Adding to 21313121221081 its reverse (18012212131312), we get a palindrome (39325333352393).

The spelling of 21313121221081 in words is "twenty-one trillion, three hundred thirteen billion, one hundred twenty-one million, two hundred twenty-one thousand, eighty-one".