21384505 has 8 divisors (see below), whose sum is σ = 25706952. Its totient is φ = 17077248.

The previous prime is 21384479. The next prime is 21384509. The reversal of 21384505 is 50548312.

It can be written as a sum of positive squares in 4 ways, for example, as 881721 + 20502784 = 939^2 + 4528^2 .

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 21384505 - 2¹¹ = 21382457 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21384509) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 424 + ... + 6553.

It is an arithmetic number, because the mean of its divisors is an integer number (3213369).

Almost surely, 2^21384505 is an apocalyptic number.

It is an amenable number.

21384505 is a deficient number, since it is larger than the sum of its proper divisors (4322447).

21384505 is an equidigital number, since it uses as much as digits as its factorization.

21384505 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7595.

The product of its (nonzero) digits is 4800, while the sum is 28.

The square root of 21384505 is about 4624.3383310480. The cubic root of 21384505 is about 277.5660854971.

The spelling of 21384505 in words is "twenty-one million, three hundred eighty-four thousand, five hundred five".