21439543 has 4 divisors (see below), whose sum is σ = 22567960. Its totient is φ = 20311128.

The previous prime is 21439529. The next prime is 21439547. The reversal of 21439543 is 34593412.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21439543 - 2¹⁷ = 21308471 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21439547) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 564180 + ... + 564217.

It is an arithmetic number, because the mean of its divisors is an integer number (5641990).

Almost surely, 2^21439543 is an apocalyptic number.

21439543 is a deficient number, since it is larger than the sum of its proper divisors (1128417).

21439543 is a wasteful number, since it uses less digits than its factorization.

21439543 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1128416.

The product of its digits is 12960, while the sum is 31.

The square root of 21439543 is about 4630.2854123693. The cubic root of 21439543 is about 277.8040084681.

The spelling of 21439543 in words is "twenty-one million, four hundred thirty-nine thousand, five hundred forty-three".