21012131232 has 144 divisors (see below), whose sum is σ = 60635615040. Its totient is φ = 6901364736.

The previous prime is 21012131209. The next prime is 21012131311. The reversal of 21012131232 is 23213121012.

It is a tau number, because it is divible by the number of its divisors (144).

It is a Harshad number since it is a multiple of its sum of digits (18).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 5823573 + ... + 5827179.

It is an arithmetic number, because the mean of its divisors is an integer number (421080660).

Almost surely, 2^21012131232 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 21012131232, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30317807520).

21012131232 is an abundant number, since it is smaller than the sum of its proper divisors (39623483808).

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

21012131232 is a wasteful number, since it uses less digits than its factorization.

21012131232 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3915 (or 3904 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 18.

Adding to 21012131232 its reverse (23213121012), we get a palindrome (44225252244).

The spelling of 21012131232 in words is "twenty-one billion, twelve million, one hundred thirty-one thousand, two hundred thirty-two".