21543804 has 18 divisors (see below), whose sum is σ = 54458040. Its totient is φ = 7181256.

The previous prime is 21543803. The next prime is 21543829. The reversal of 21543804 is 40834512.

It is a tau number, because it is divible by the number of its divisors (18).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21543803) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 299184 + ... + 299255.

Almost surely, 2^21543804 is an apocalyptic number.

It is an amenable number.

21543804 is an abundant number, since it is smaller than the sum of its proper divisors (32914236).

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

21543804 is a wasteful number, since it uses less digits than its factorization.

21543804 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 598449 (or 598444 counting only the distinct ones).

The product of its (nonzero) digits is 3840, while the sum is 27.

The square root of 21543804 is about 4641.5303510803. The cubic root of 21543804 is about 278.2536029253.

The spelling of 21543804 in words is "twenty-one million, five hundred forty-three thousand, eight hundred four".