21289843 has 2 divisors, whose sum is σ = 21289844. Its totient is φ = 21289842.

The previous prime is 21289841. The next prime is 21289867. The reversal of 21289843 is 34898212.

21289843 is nontrivially palindromic in base 12.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21289843 - 2¹ = 21289841 is a prime.

Together with 21289841, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (21289841) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10644921 + 10644922.

It is an arithmetic number, because the mean of its divisors is an integer number (10644922).

Almost surely, 2^21289843 is an apocalyptic number.

21289843 is a deficient number, since it is larger than the sum of its proper divisors (1).

21289843 is an equidigital number, since it uses as much as digits as its factorization.

21289843 is an evil number, because the sum of its binary digits is even.

The product of its digits is 27648, while the sum is 37.

The square root of 21289843 is about 4614.0917849562. The cubic root of 21289843 is about 277.1559158198.

The spelling of 21289843 in words is "twenty-one million, two hundred eighty-nine thousand, eight hundred forty-three".