21203134420 has 96 divisors (see below), whose sum is σ = 50049407520. Its totient is φ = 7493591040.

The previous prime is 21203134411. The next prime is 21203134423. The reversal of 21203134420 is 2443130212.

It can be written as a sum of positive squares in 16 ways, for example, as 17428752324 + 3774382096 = 132018^2 + 61436^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21203134391 and 21203134400.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21203134423) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 546216 + ... + 583744.

It is an arithmetic number, because the mean of its divisors is an integer number (521347995).

Almost surely, 2^21203134420 is an apocalyptic number.

21203134420 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 21203134420, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25024703760).

21203134420 is an abundant number, since it is smaller than the sum of its proper divisors (28846273100).

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

21203134420 is a wasteful number, since it uses less digits than its factorization.

21203134420 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 37645 (or 37643 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 22.

Adding to 21203134420 its reverse (2443130212), we get a palindrome (23646264632).

The spelling of 21203134420 in words is "twenty-one billion, two hundred three million, one hundred thirty-four thousand, four hundred twenty".