21212143 has 2 divisors, whose sum is σ = 21212144. Its totient is φ = 21212142.

The previous prime is 21212131. The next prime is 21212159. The reversal of 21212143 is 34121212.

It is an a-pointer prime, because the next prime (21212159) can be obtained adding 21212143 to its sum of digits (16).

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21212143 - 2⁵ = 21212111 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 (21212183) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10606071 + 10606072.

It is an arithmetic number, because the mean of its divisors is an integer number (10606072).

Almost surely, 2^21212143 is an apocalyptic number.

21212143 is a deficient number, since it is larger than the sum of its proper divisors (1).

21212143 is an equidigital number, since it uses as much as digits as its factorization.

21212143 is an evil number, because the sum of its binary digits is even.

The product of its digits is 96, while the sum is 16.

The square root of 21212143 is about 4605.6642300541. The cubic root of 21212143 is about 276.8183328361.

Adding to 21212143 its reverse (34121212), we get a palindrome (55333355).

The spelling of 21212143 in words is "twenty-one million, two hundred twelve thousand, one hundred forty-three".