21101212123 has 2 divisors, whose sum is σ = 21101212124. Its totient is φ = 21101212122.

The previous prime is 21101212103. The next prime is 21101212133. The reversal of 21101212123 is 32121210112.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21101212123 - 2⁹ = 21101211611 is a prime.

It is a super-2 number, since 2×21101212123² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21101212097 and 21101212106.

It is not a weakly prime, because it can be changed into another prime (21101212103) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10550606061 + 10550606062.

It is an arithmetic number, because the mean of its divisors is an integer number (10550606062).

Almost surely, 2^21101212123 is an apocalyptic number.

21101212123 is a deficient number, since it is larger than the sum of its proper divisors (1).

21101212123 is an equidigital number, since it uses as much as digits as its factorization.

21101212123 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 48, while the sum is 16.

Adding to 21101212123 its reverse (32121210112), we get a palindrome (53222422235).

The spelling of 21101212123 in words is "twenty-one billion, one hundred one million, two hundred twelve thousand, one hundred twenty-three".