21231984 has 20 divisors (see below), whose sum is σ = 54849416. Its totient is φ = 7077312.

The previous prime is 21231979. The next prime is 21232007. The reversal of 21231984 is 48913212.

It is a Smith number, since the sum of its digits (30) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 221119 + ... + 221214.

Almost surely, 2^21231984 is an apocalyptic number.

21231984 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21231984 is an abundant number, since it is smaller than the sum of its proper divisors (33617432).

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

21231984 is a wasteful number, since it uses less digits than its factorization.

21231984 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 442344 (or 442338 counting only the distinct ones).

The product of its digits is 3456, while the sum is 30.

The square root of 21231984 is about 4607.8177047275. The cubic root of 21231984 is about 276.9046142487.

The spelling of 21231984 in words is "twenty-one million, two hundred thirty-one thousand, nine hundred eighty-four".