21384521 has 8 divisors (see below), whose sum is σ = 22692384. Its totient is φ = 20082240.

The previous prime is 21384511. The next prime is 21384529. The reversal of 21384521 is 12548312.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21384521 - 2¹⁰ = 21383497 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21384529) 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 in 7 ways as a sum of consecutive naturals, for example, 8606 + ... + 10808.

It is an arithmetic number, because the mean of its divisors is an integer number (2836548).

Almost surely, 2^21384521 is an apocalyptic number.

It is an amenable number.

21384521 is a deficient number, since it is larger than the sum of its proper divisors (1307863).

21384521 is a wasteful number, since it uses less digits than its factorization.

21384521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2791.

The product of its digits is 1920, while the sum is 26.

The square root of 21384521 is about 4624.3400610249. The cubic root of 21384521 is about 277.5661547226.

The spelling of 21384521 in words is "twenty-one million, three hundred eighty-four thousand, five hundred twenty-one".