21121221193 has 2 divisors, whose sum is σ = 21121221194. Its totient is φ = 21121221192.

The previous prime is 21121221157. The next prime is 21121221221. The reversal of 21121221193 is 39112212112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17046696969 + 4074524224 = 130563^2 + 63832^2 .

It is a cyclic number.

It is not a de Polignac number, because 21121221193 - 2²¹ = 21119124041 is a prime.

It is a super-2 number, since 2×21121221193² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21121221113) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10560610596 + 10560610597.

It is an arithmetic number, because the mean of its divisors is an integer number (10560610597).

Almost surely, 2^21121221193 is an apocalyptic number.

It is an amenable number.

21121221193 is a deficient number, since it is larger than the sum of its proper divisors (1).

21121221193 is an equidigital number, since it uses as much as digits as its factorization.

21121221193 is an evil number, because the sum of its binary digits is even.

The product of its digits is 432, while the sum is 25.

The spelling of 21121221193 in words is "twenty-one billion, one hundred twenty-one million, two hundred twenty-one thousand, one hundred ninety-three".