21013984 has 12 divisors (see below), whose sum is σ = 41371344. Its totient is φ = 10506976.

The previous prime is 21013961. The next prime is 21013987. The reversal of 21013984 is 48931012.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21013987) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 328312 + ... + 328375.

It is an arithmetic number, because the mean of its divisors is an integer number (3447612).

Almost surely, 2^21013984 is an apocalyptic number.

It is an amenable number.

21013984 is a deficient number, since it is larger than the sum of its proper divisors (20357360).

21013984 is an equidigital number, since it uses as much as digits as its factorization.

21013984 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 656697 (or 656689 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 28.

The square root of 21013984 is about 4584.1012205230. The cubic root of 21013984 is about 275.9536434082.

Adding to 21013984 its reverse (48931012), we get a palindrome (69944996).

The spelling of 21013984 in words is "twenty-one million, thirteen thousand, nine hundred eighty-four".