21121110221993 has 2 divisors, whose sum is σ = 21121110221994. Its totient is φ = 21121110221992.

The previous prime is 21121110221971. The next prime is 21121110222059. The reversal of 21121110221993 is 39912201112112.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21031285936144 + 89824285849 = 4585988^2 + 299707^2 .

It is a cyclic number.

It is not a de Polignac number, because 21121110221993 - 2⁸ = 21121110221737 is a prime.

It is a super-2 number, since 2×21121110221993² (a number of 27 digits) contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (21121110221903) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10560555110996 + 10560555110997.

It is an arithmetic number, because the mean of its divisors is an integer number (10560555110997).

Almost surely, 2^{21121110221993} is an apocalyptic number.

It is an amenable number.

21121110221993 is a deficient number, since it is larger than the sum of its proper divisors (1).

21121110221993 is an equidigital number, since it uses as much as digits as its factorization.

21121110221993 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3888, while the sum is 35.

The spelling of 21121110221993 in words is "twenty-one trillion, one hundred twenty-one billion, one hundred ten million, two hundred twenty-one thousand, nine hundred ninety-three".