21043984 has 20 divisors (see below), whose sum is σ = 43909516. Its totient is φ = 9712512.

The previous prime is 21043973. The next prime is 21043991. The reversal of 21043984 is 48934012.

It can be written as a sum of positive squares in 2 ways, for example, as 14137600 + 6906384 = 3760^2 + 2628^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 50379 + ... + 50794.

Almost surely, 2^21043984 is an apocalyptic number.

It is an amenable number.

21043984 is an abundant number, since it is smaller than the sum of its proper divisors (22865532).

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

21043984 is a wasteful number, since it uses less digits than its factorization.

21043984 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 101194 (or 101188 counting only the distinct ones).

The product of its (nonzero) digits is 6912, while the sum is 31.

The square root of 21043984 is about 4587.3722325532. The cubic root of 21043984 is about 276.0849000173.

Adding to 21043984 its reverse (48934012), we get a palindrome (69977996).

The spelling of 21043984 in words is "twenty-one million, forty-three thousand, nine hundred eighty-four".