21013123200 has 384 divisors, whose sum is σ = 71522922240. Its totient is φ = 5419008000.

The previous prime is 21013123189. The next prime is 21013123217. The reversal of 21013123200 is 232131012.

It is a tau number, because it is divible by the number of its divisors (384).

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a self number, because there is not a number n which added to its sum of digits gives 21013123200.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 77539065 + ... + 77539335.

It is an arithmetic number, because the mean of its divisors is an integer number (186257610).

Almost surely, 2^21013123200 is an apocalyptic number.

21013123200 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 21013123200, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35761461120).

21013123200 is an abundant number, since it is smaller than the sum of its proper divisors (50509799040).

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

21013123200 is a wasteful number, since it uses less digits than its factorization.

21013123200 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 536 (or 519 counting only the distinct ones).

The product of its (nonzero) digits is 72, while the sum is 15.

Adding to 21013123200 its reverse (232131012), we get a palindrome (21245254212).

The spelling of 21013123200 in words is "twenty-one billion, thirteen million, one hundred twenty-three thousand, two hundred".