21215143 has 2 divisors, whose sum is σ = 21215144. Its totient is φ = 21215142.

The previous prime is 21215141. The next prime is 21215147. The reversal of 21215143 is 34151212.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21215143 - 2¹ = 21215141 is a prime.

Together with 21215141, it forms a pair of twin primes.

It is a self number, because there is not a number n which added to its sum of digits gives 21215143.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21215141) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10607571 + 10607572.

It is an arithmetic number, because the mean of its divisors is an integer number (10607572).

Almost surely, 2^21215143 is an apocalyptic number.

21215143 is a deficient number, since it is larger than the sum of its proper divisors (1).

21215143 is an equidigital number, since it uses as much as digits as its factorization.

21215143 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 240, while the sum is 19.

The square root of 21215143 is about 4605.9899044614. The cubic root of 21215143 is about 276.8313822146.

Adding to 21215143 its reverse (34151212), we get a palindrome (55366355).

The spelling of 21215143 in words is "twenty-one million, two hundred fifteen thousand, one hundred forty-three".