21203440128 has 480 divisors, whose sum is σ = 71423928576. Its totient is φ = 5996150784.

The previous prime is 21203440117. The next prime is 21203440129. The reversal of 21203440128 is 82104430212.

21203440128 is a `hidden beast` number, since 2 + 1 + 203 + 440 + 12 + 8 = 666.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21203440129) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 47863075 + ... + 47863517.

Almost surely, 2^21203440128 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21203440128, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35711964288).

21203440128 is an abundant number, since it is smaller than the sum of its proper divisors (50220488448).

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

21203440128 is a wasteful number, since it uses less digits than its factorization.

21203440128 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 544 (or 525 counting only the distinct ones).

The product of its (nonzero) digits is 3072, while the sum is 27.

The spelling of 21203440128 in words is "twenty-one billion, two hundred three million, four hundred forty thousand, one hundred twenty-eight".