21867984 has 60 divisors (see below), whose sum is σ = 64807236. Its totient is φ = 6859776.

The previous prime is 21867983. The next prime is 21868013. The reversal of 21867984 is 48976812.

It can be written as a sum of positive squares in 2 ways, for example, as 11370384 + 10497600 = 3372^2 + 3240^2 .

It is a Smith number, since the sum of its digits (45) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21867983) by changing a digit.

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 11 ways as a sum of consecutive naturals, for example, 2019 + ... + 6914.

Almost surely, 2^21867984 is an apocalyptic number.

21867984 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21867984 is an abundant number, since it is smaller than the sum of its proper divisors (42939252).

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

21867984 is a wasteful number, since it uses less digits than its factorization.

21867984 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8964 (or 8955 counting only the distinct ones).

The product of its digits is 193536, while the sum is 45.

The square root of 21867984 is about 4676.3216313680. The cubic root of 21867984 is about 279.6423324313.

The spelling of 21867984 in words is "twenty-one million, eight hundred sixty-seven thousand, nine hundred eighty-four".