21084311 has 2 divisors, whose sum is σ = 21084312. Its totient is φ = 21084310.

The previous prime is 21084289. The next prime is 21084313. The reversal of 21084311 is 11348012.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21084311 - 2¹⁴ = 21067927 is a prime.

Together with 21084313, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21084313) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10542155 + 10542156.

It is an arithmetic number, because the mean of its divisors is an integer number (10542156).

Almost surely, 2^21084311 is an apocalyptic number.

21084311 is the 2054-th centered decagonal number.

21084311 is a deficient number, since it is larger than the sum of its proper divisors (1).

21084311 is an equidigital number, since it uses as much as digits as its factorization.

21084311 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 192, while the sum is 20.

The square root of 21084311 is about 4591.7655645732. The cubic root of 21084311 is about 276.2611431252.

The spelling of 21084311 in words is "twenty-one million, eighty-four thousand, three hundred eleven".