21231732 has 24 divisors (see below), whose sum is σ = 50139936. Its totient is φ = 6991648.

The previous prime is 21231731. The next prime is 21231757. The reversal of 21231732 is 23713212.

It is a junction number, because it is equal to n+sod(n) for n = 21231699 and 21231708.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21231731) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9663 + ... + 11654.

It is an arithmetic number, because the mean of its divisors is an integer number (2089164).

It is a self-describing number.

Almost surely, 2^21231732 is an apocalyptic number.

It is an amenable number.

21231732 is an abundant number, since it is smaller than the sum of its proper divisors (28908204).

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

21231732 is a wasteful number, since it uses less digits than its factorization.

21231732 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21407 (or 21405 counting only the distinct ones).

The product of its digits is 504, while the sum is 21.

The square root of 21231732 is about 4607.7903598146. The cubic root of 21231732 is about 276.9035187279.

Adding to 21231732 its reverse (23713212), we get a palindrome (44944944).

The spelling of 21231732 in words is "twenty-one million, two hundred thirty-one thousand, seven hundred thirty-two".