21531200432 has 80 divisors (see below), whose sum is σ = 49220308032. Its totient is φ = 8931409920.

The previous prime is 21531200419. The next prime is 21531200437. The reversal of 21531200432 is 23400213512.

It is a junction number, because it is equal to n+sod(n) for n = 21531200398 and 21531200407.

It is not an unprimeable number, because it can be changed into a prime (21531200437) 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, 786332 + ... + 813252.

Almost surely, 2^21531200432 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 21531200432, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24610154016).

21531200432 is an abundant number, since it is smaller than the sum of its proper divisors (27689107600).

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

21531200432 is a wasteful number, since it uses less digits than its factorization.

21531200432 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27166 (or 27160 counting only the distinct ones).

The product of its (nonzero) digits is 1440, while the sum is 23.

Adding to 21531200432 its reverse (23400213512), we get a palindrome (44931413944).

The spelling of 21531200432 in words is "twenty-one billion, five hundred thirty-one million, two hundred thousand, four hundred thirty-two".