21405234432 has 72 divisors (see below), whose sum is σ = 57015908320. Its totient is φ = 7129221120.

The previous prime is 21405234371. The next prime is 21405234439. The reversal of 21405234432 is 23443250412.

It is a super-2 number, since 2×21405234432² (a number of 21 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21405234432.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21405234439) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 980694 + ... + 1002282.

Almost surely, 2^21405234432 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 21405234432, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28507954160).

21405234432 is an abundant number, since it is smaller than the sum of its proper divisors (35610673888).

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

21405234432 is a wasteful number, since it uses less digits than its factorization.

21405234432 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22899 (or 22885 counting only the distinct ones).

The product of its (nonzero) digits is 23040, while the sum is 30.

Adding to 21405234432 its reverse (23443250412), we get a palindrome (44848484844).

The spelling of 21405234432 in words is "twenty-one billion, four hundred five million, two hundred thirty-four thousand, four hundred thirty-two".