21018084 has 12 divisors (see below), whose sum is σ = 49042224. Its totient is φ = 7006024.

The previous prime is 21018079. The next prime is 21018091. The reversal of 21018084 is 48081012.

It is a tau number, because it is divible by the number of its divisors (12).

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 875742 + ... + 875765.

It is an arithmetic number, because the mean of its divisors is an integer number (4086852).

Almost surely, 2^21018084 is an apocalyptic number.

It is an amenable number.

21018084 is an abundant number, since it is smaller than the sum of its proper divisors (28024140).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21018084 is a wasteful number, since it uses less digits than its factorization.

21018084 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1751514 (or 1751512 counting only the distinct ones).

The product of its (nonzero) digits is 512, while the sum is 24.

The square root of 21018084 is about 4584.5483965163. The cubic root of 21018084 is about 275.9715891781.

Adding to 21018084 its reverse (48081012), we get a palindrome (69099096).

The spelling of 21018084 in words is "twenty-one million, eighteen thousand, eighty-four".