21021010123 has 2 divisors, whose sum is σ = 21021010124. Its totient is φ = 21021010122.

The previous prime is 21021010121. The next prime is 21021010141. The reversal of 21021010123 is 32101012012.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21021010123 - 2¹ = 21021010121 is a prime.

Together with 21021010121, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (21021010121) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10510505061 + 10510505062.

It is an arithmetic number, because the mean of its divisors is an integer number (10510505062).

Almost surely, 2^21021010123 is an apocalyptic number.

21021010123 is a deficient number, since it is larger than the sum of its proper divisors (1).

21021010123 is an equidigital number, since it uses as much as digits as its factorization.

21021010123 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 24, while the sum is 13.

Adding to 21021010123 its reverse (32101012012), we get a palindrome (53122022135).

The spelling of 21021010123 in words is "twenty-one billion, twenty-one million, ten thousand, one hundred twenty-three".