21210123123 has 24 divisors (see below), whose sum is σ = 35194974048. Its totient is φ = 12057265152.

The previous prime is 21210123113. The next prime is 21210123133. The reversal of 21210123123 is 32132101212.

It is an interprime number because it is at equal distance from previous prime (21210123113) and next prime (21210123133).

It is not a de Polignac number, because 21210123123 - 2⁴ = 21210123107 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21210123096 and 21210123105.

It is not an unprimeable number, because it can be changed into a prime (21210123113) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 860040 + ... + 884357.

It is an arithmetic number, because the mean of its divisors is an integer number (1466457252).

Almost surely, 2^21210123123 is an apocalyptic number.

21210123123 is a deficient number, since it is larger than the sum of its proper divisors (13984850925).

21210123123 is a wasteful number, since it uses less digits than its factorization.

21210123123 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1744603 (or 1744600 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 18.

Adding to 21210123123 its reverse (32132101212), we get a palindrome (53342224335).

The spelling of 21210123123 in words is "twenty-one billion, two hundred ten million, one hundred twenty-three thousand, one hundred twenty-three".