21022543 has 4 divisors (see below), whose sum is σ = 21037968. Its totient is φ = 21007120.

The previous prime is 21022541. The next prime is 21022553. The reversal of 21022543 is 34522012.

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 21022543 - 2¹ = 21022541 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21022543.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21022541) 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, 5446 + ... + 8467.

It is an arithmetic number, because the mean of its divisors is an integer number (5259492).

Almost surely, 2^21022543 is an apocalyptic number.

21022543 is a deficient number, since it is larger than the sum of its proper divisors (15425).

21022543 is a wasteful number, since it uses less digits than its factorization.

21022543 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15424.

The product of its (nonzero) digits is 480, while the sum is 19.

The square root of 21022543 is about 4585.0346781677. The cubic root of 21022543 is about 275.9911036480.

Adding to 21022543 its reverse (34522012), we get a palindrome (55544555).

The spelling of 21022543 in words is "twenty-one million, twenty-two thousand, five hundred forty-three".