21812143 has 2 divisors, whose sum is σ = 21812144. Its totient is φ = 21812142.

The previous prime is 21812113. The next prime is 21812149. The reversal of 21812143 is 34121812.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21812143 - 2⁵ = 21812111 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21812149) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10906071 + 10906072.

It is an arithmetic number, because the mean of its divisors is an integer number (10906072).

Almost surely, 2^21812143 is an apocalyptic number.

21812143 is a deficient number, since it is larger than the sum of its proper divisors (1).

21812143 is an equidigital number, since it uses as much as digits as its factorization.

21812143 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 384, while the sum is 22.

The square root of 21812143 is about 4670.3472033672. The cubic root of 21812143 is about 279.4041026058.

Adding to 21812143 its reverse (34121812), we get a palindrome (55933955).

The spelling of 21812143 in words is "twenty-one million, eight hundred twelve thousand, one hundred forty-three".