21384517 has 16 divisors (see below), whose sum is σ = 26836992. Its totient is φ = 16553520.

The previous prime is 21384511. The next prime is 21384529. The reversal of 21384517 is 71548312.

It is a cyclic number.

It is not a de Polignac number, because 21384517 - 2³ = 21384509 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21384511) 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 15 ways as a sum of consecutive naturals, for example, 12028 + ... + 13690.

It is an arithmetic number, because the mean of its divisors is an integer number (1677312).

Almost surely, 2^21384517 is an apocalyptic number.

It is an amenable number.

21384517 is a deficient number, since it is larger than the sum of its proper divisors (5452475).

21384517 is a wasteful number, since it uses less digits than its factorization.

21384517 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1848.

The product of its digits is 6720, while the sum is 31.

The square root of 21384517 is about 4624.3396285308. The cubic root of 21384517 is about 277.5661374162.

The spelling of 21384517 in words is "twenty-one million, three hundred eighty-four thousand, five hundred seventeen".