21012223123 has 2 divisors, whose sum is σ = 21012223124. Its totient is φ = 21012223122.

The previous prime is 21012223117. The next prime is 21012223163. The reversal of 21012223123 is 32132221012.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21012223123 - 2⁹ = 21012222611 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21012223123.

It is not a weakly prime, because it can be changed into another prime (21012223103) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10506111561 + 10506111562.

It is an arithmetic number, because the mean of its divisors is an integer number (10506111562).

Almost surely, 2^21012223123 is an apocalyptic number.

21012223123 is a deficient number, since it is larger than the sum of its proper divisors (1).

21012223123 is an equidigital number, since it uses as much as digits as its factorization.

21012223123 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 288, while the sum is 19.

Adding to 21012223123 its reverse (32132221012), we get a palindrome (53144444135).

The spelling of 21012223123 in words is "twenty-one billion, twelve million, two hundred twenty-three thousand, one hundred twenty-three".