21384511 has 2 divisors, whose sum is σ = 21384512. Its totient is φ = 21384510.

The previous prime is 21384509. The next prime is 21384529. The reversal of 21384511 is 11548312.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21384511 - 2¹ = 21384509 is a prime.

Together with 21384509, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21382511) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10692255 + 10692256.

It is an arithmetic number, because the mean of its divisors is an integer number (10692256).

Almost surely, 2^21384511 is an apocalyptic number.

21384511 is a deficient number, since it is larger than the sum of its proper divisors (1).

21384511 is an equidigital number, since it uses as much as digits as its factorization.

21384511 is an evil number, because the sum of its binary digits is even.

The product of its digits is 960, while the sum is 25.

The square root of 21384511 is about 4624.3389797894. The cubic root of 21384511 is about 277.5661114567.

The spelling of 21384511 in words is "twenty-one million, three hundred eighty-four thousand, five hundred eleven".