21431143 has 4 divisors (see below), whose sum is σ = 21452368. Its totient is φ = 21409920.

The previous prime is 21431141. The next prime is 21431149. The reversal of 21431143 is 34113412.

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 21431143 - 2¹ = 21431141 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21431143.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21431141) 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, 9018 + ... + 11143.

It is an arithmetic number, because the mean of its divisors is an integer number (5363092).

Almost surely, 2^21431143 is an apocalyptic number.

21431143 is a deficient number, since it is larger than the sum of its proper divisors (21225).

21431143 is a wasteful number, since it uses less digits than its factorization.

21431143 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21224.

The product of its digits is 288, while the sum is 19.

The square root of 21431143 is about 4629.3782519902. The cubic root of 21431143 is about 277.7677225812.

Adding to 21431143 its reverse (34113412), we get a palindrome (55544555).

The spelling of 21431143 in words is "twenty-one million, four hundred thirty-one thousand, one hundred forty-three".