21072984 has 16 divisors (see below), whose sum is σ = 52682520. Its totient is φ = 7024320.

The previous prime is 21072973. The next prime is 21073001. The reversal of 21072984 is 48927012.

It is a happy number.

It is a hoax number, since the sum of its digits (33) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

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, 438997 + ... + 439044.

Almost surely, 2^21072984 is an apocalyptic number.

21072984 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21072984 is an abundant number, since it is smaller than the sum of its proper divisors (31609536).

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

21072984 is a wasteful number, since it uses less digits than its factorization.

21072984 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 878050 (or 878046 counting only the distinct ones).

The product of its (nonzero) digits is 8064, while the sum is 33.

The square root of 21072984 is about 4590.5319953138. The cubic root of 21072984 is about 276.2116628822.

Adding to 21072984 its reverse (48927012), we get a palindrome (69999996).

The spelling of 21072984 in words is "twenty-one million, seventy-two thousand, nine hundred eighty-four".