21221543 has 8 divisors (see below), whose sum is σ = 24281088. Its totient is φ = 18168984.

The previous prime is 21221539. The next prime is 21221561. The reversal of 21221543 is 34512212.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21221543 - 2² = 21221539 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 (21221503) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 10730 + ... + 12552.

It is an arithmetic number, because the mean of its divisors is an integer number (3035136).

Almost surely, 2^21221543 is an apocalyptic number.

21221543 is a deficient number, since it is larger than the sum of its proper divisors (3059545).

21221543 is a wasteful number, since it uses less digits than its factorization.

21221543 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3493.

The product of its digits is 480, while the sum is 20.

The square root of 21221543 is about 4606.6845995792. The cubic root of 21221543 is about 276.8592167778.

Adding to 21221543 its reverse (34512212), we get a palindrome (55733755).

The spelling of 21221543 in words is "twenty-one million, two hundred twenty-one thousand, five hundred forty-three".