21130402123 has 2 divisors, whose sum is σ = 21130402124. Its totient is φ = 21130402122.

The previous prime is 21130402121. The next prime is 21130402133. The reversal of 21130402123 is 32120403112.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21130402123 - 2¹ = 21130402121 is a prime.

Together with 21130402121, it forms a pair of twin primes.

It is a self number, because there is not a number n which added to its sum of digits gives 21130402123.

It is not a weakly prime, because it can be changed into another prime (21130402121) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10565201061 + 10565201062.

It is an arithmetic number, because the mean of its divisors is an integer number (10565201062).

Almost surely, 2^21130402123 is an apocalyptic number.

21130402123 is a deficient number, since it is larger than the sum of its proper divisors (1).

21130402123 is an equidigital number, since it uses as much as digits as its factorization.

21130402123 is an odious number, because the sum of its binary digits is odd.

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

Adding to 21130402123 its reverse (32120403112), we get a palindrome (53250805235).

The spelling of 21130402123 in words is "twenty-one billion, one hundred thirty million, four hundred two thousand, one hundred twenty-three".