21984539 has 6 divisors (see below), whose sum is σ = 23202900. Its totient is φ = 20827116.

The previous prime is 21984533. The next prime is 21984593. The reversal of 21984539 is 93548912.

It is not a de Polignac number, because 21984539 - 2¹⁶ = 21919003 is a prime.

It is a super-3 number, since 3×21984539³ (a number of 23 digits) contains 333 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21984496 and 21984505.

It is not an unprimeable number, because it can be changed into a prime (21984533) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 30089 + ... + 30810.

It is an arithmetic number, because the mean of its divisors is an integer number (3867150).

Almost surely, 2^21984539 is an apocalyptic number.

21984539 is a deficient number, since it is larger than the sum of its proper divisors (1218361).

21984539 is an equidigital number, since it uses as much as digits as its factorization.

21984539 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 60937 (or 60918 counting only the distinct ones).

The product of its digits is 77760, while the sum is 41.

The square root of 21984539 is about 4688.7673220155. The cubic root of 21984539 is about 280.1382777888.

The spelling of 21984539 in words is "twenty-one million, nine hundred eighty-four thousand, five hundred thirty-nine".