21301312123 has 24 divisors (see below), whose sum is σ = 26374738848. Its totient is φ = 16845034752.

The previous prime is 21301312051. The next prime is 21301312139. The reversal of 21301312123 is 32121310312.

It is not a de Polignac number, because 21301312123 - 2⁹ = 21301311611 is a prime.

It is a super-2 number, since 2×21301312123² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21301312123.

It is not an unprimeable number, because it can be changed into a prime (21301312163) 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, 3206161 + ... + 3212797.

It is an arithmetic number, because the mean of its divisors is an integer number (1098947452).

Almost surely, 2^21301312123 is an apocalyptic number.

21301312123 is a deficient number, since it is larger than the sum of its proper divisors (5073426725).

21301312123 is a wasteful number, since it uses less digits than its factorization.

21301312123 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9383 (or 9370 counting only the distinct ones).

The product of its (nonzero) digits is 216, while the sum is 19.

Adding to 21301312123 its reverse (32121310312), we get a palindrome (53422622435).

The spelling of 21301312123 in words is "twenty-one billion, three hundred one million, three hundred twelve thousand, one hundred twenty-three".