21123253120 has 128 divisors (see below), whose sum is σ = 51256346400. Its totient is φ = 8323276800.

The previous prime is 21123253111. The next prime is 21123253127. The reversal of 21123253120 is 2135232112.

It is a tau number, because it is divible by the number of its divisors (128).

It is a junction number, because it is equal to n+sod(n) for n = 21123253091 and 21123253100.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21123253127) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 14801847 + ... + 14803273.

Almost surely, 2^21123253120 is an apocalyptic number.

21123253120 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21123253120, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25628173200).

21123253120 is an abundant number, since it is smaller than the sum of its proper divisors (30133093280).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21123253120 is a wasteful number, since it uses less digits than its factorization.

21123253120 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1776 (or 1764 counting only the distinct ones).

The product of its (nonzero) digits is 720, while the sum is 22.

Adding to 21123253120 its reverse (2135232112), we get a palindrome (23258485232).

The spelling of 21123253120 in words is "twenty-one billion, one hundred twenty-three million, two hundred fifty-three thousand, one hundred twenty".