21404143 has 4 divisors (see below), whose sum is σ = 21420328. Its totient is φ = 21387960.

The previous prime is 21404101. The next prime is 21404147. The reversal of 21404143 is 34140412.

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 21404143 - 2¹⁷ = 21273071 is a prime.

It is a Duffinian number.

It is a plaindrome in base 16.

It is a self number, because there is not a number n which added to its sum of digits gives 21404143.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21404147) 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, 5913 + ... + 8818.

It is an arithmetic number, because the mean of its divisors is an integer number (5355082).

Almost surely, 2^21404143 is an apocalyptic number.

21404143 is a deficient number, since it is larger than the sum of its proper divisors (16185).

21404143 is a wasteful number, since it uses less digits than its factorization.

21404143 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16184.

The product of its (nonzero) digits is 384, while the sum is 19.

The square root of 21404143 is about 4626.4611745912. The cubic root of 21404143 is about 277.6510251155.

Adding to 21404143 its reverse (34140412), we get a palindrome (55544555).

The spelling of 21404143 in words is "twenty-one million, four hundred four thousand, one hundred forty-three".