21555443 has 36 divisors (see below), whose sum is σ = 28789560. Its totient is φ = 16039296.

The previous prime is 21555433. The next prime is 21555449. The reversal of 21555443 is 34455512.

It is not a de Polignac number, because 21555443 - 2¹⁴ = 21539059 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21555449) 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 35 ways as a sum of consecutive naturals, for example, 157271 + ... + 157407.

It is an arithmetic number, because the mean of its divisors is an integer number (799710).

Almost surely, 2^21555443 is an apocalyptic number.

21555443 is a deficient number, since it is larger than the sum of its proper divisors (7234117).

21555443 is a wasteful number, since it uses less digits than its factorization.

21555443 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 196 (or 176 counting only the distinct ones).

The product of its digits is 12000, while the sum is 29.

The square root of 21555443 is about 4642.7839708520. The cubic root of 21555443 is about 278.3037025680.

The spelling of 21555443 in words is "twenty-one million, five hundred fifty-five thousand, four hundred forty-three".