21121110281 has 2 divisors, whose sum is σ = 21121110282. Its totient is φ = 21121110280.

The previous prime is 21121110253. The next prime is 21121110287. The reversal of 21121110281 is 18201112112.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14711506681 + 6409603600 = 121291^2 + 80060^2 .

It is a cyclic number.

It is not a de Polignac number, because 21121110281 - 2¹⁰ = 21121109257 is a prime.

It is a super-2 number, since 2×21121110281² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21121110287) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10560555140 + 10560555141.

It is an arithmetic number, because the mean of its divisors is an integer number (10560555141).

Almost surely, 2^21121110281 is an apocalyptic number.

It is an amenable number.

21121110281 is a deficient number, since it is larger than the sum of its proper divisors (1).

21121110281 is an equidigital number, since it uses as much as digits as its factorization.

21121110281 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 64, while the sum is 20.

Adding to 21121110281 its reverse (18201112112), we get a palindrome (39322222393).

The spelling of 21121110281 in words is "twenty-one billion, one hundred twenty-one million, one hundred ten thousand, two hundred eighty-one".