21332431 has 4 divisors (see below), whose sum is σ = 22259952. Its totient is φ = 20404912.

The previous prime is 21332419. The next prime is 21332471. The reversal of 21332431 is 13423312.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21332431 - 2¹¹ = 21330383 is a prime.

It is a super-2 number, since 2×21332431² = 910145224739522, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21332399 and 21332408.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21332401) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 463726 + ... + 463771.

It is an arithmetic number, because the mean of its divisors is an integer number (5564988).

Almost surely, 2^21332431 is an apocalyptic number.

21332431 is a deficient number, since it is larger than the sum of its proper divisors (927521).

21332431 is an equidigital number, since it uses as much as digits as its factorization.

21332431 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 927520.

The product of its digits is 432, while the sum is 19.

The square root of 21332431 is about 4618.7044720354. The cubic root of 21332431 is about 277.3405994164.

Adding to 21332431 its reverse (13423312), we get a palindrome (34755743).

The spelling of 21332431 in words is "twenty-one million, three hundred thirty-two thousand, four hundred thirty-one".