21210123232123 has 4 divisors (see below), whose sum is σ = 24240140836720. Its totient is φ = 18180105627528.

The previous prime is 21210123232099. The next prime is 21210123232157. The reversal of 21210123232123 is 32123232101212.

21210123232123 is an esthetic number in base 10, because in such base its adjacent digits differ by 1.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21210123232123 is a prime.

It is a super-2 number, since 2×21210123232123² (a number of 27 digits) contains 22 as substring.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21210123232523) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1515008802288 + ... + 1515008802301.

It is an arithmetic number, because the mean of its divisors is an integer number (6060035209180).

Almost surely, 2^{21210123232123} is an apocalyptic number.

21210123232123 is a deficient number, since it is larger than the sum of its proper divisors (3030017604597).

21210123232123 is an equidigital number, since it uses as much as digits as its factorization.

21210123232123 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3030017604596.

The product of its (nonzero) digits is 1728, while the sum is 25.

Adding to 21210123232123 its reverse (32123232101212), we get a palindrome (53333355333335).

The spelling of 21210123232123 in words is "twenty-one trillion, two hundred ten billion, one hundred twenty-three million, two hundred thirty-two thousand, one hundred twenty-three".