21284911 has 2 divisors, whose sum is σ = 21284912. Its totient is φ = 21284910.

The previous prime is 21284903. The next prime is 21284917. The reversal of 21284911 is 11948212.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21284911 - 2³ = 21284903 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21284911.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21284917) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10642455 + 10642456.

It is an arithmetic number, because the mean of its divisors is an integer number (10642456).

Almost surely, 2^21284911 is an apocalyptic number.

21284911 is a deficient number, since it is larger than the sum of its proper divisors (1).

21284911 is an equidigital number, since it uses as much as digits as its factorization.

21284911 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1152, while the sum is 28.

The square root of 21284911 is about 4613.5573042935. The cubic root of 21284911 is about 277.1345122089.

The spelling of 21284911 in words is "twenty-one million, two hundred eighty-four thousand, nine hundred eleven".