21571223 has 4 divisors (see below), whose sum is σ = 21700560. Its totient is φ = 21441888.

The previous prime is 21571169. The next prime is 21571229. The reversal of 21571223 is 32217512.

It is a happy number.

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 21571223 - 2¹⁴ = 21554839 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 (21571229) 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, 64418 + ... + 64751.

It is an arithmetic number, because the mean of its divisors is an integer number (5425140).

Almost surely, 2^21571223 is an apocalyptic number.

21571223 is a deficient number, since it is larger than the sum of its proper divisors (129337).

21571223 is a wasteful number, since it uses less digits than its factorization.

21571223 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 129336.

The product of its digits is 840, while the sum is 23.

The square root of 21571223 is about 4644.4830713439. The cubic root of 21571223 is about 278.3715981989.

Adding to 21571223 its reverse (32217512), we get a palindrome (53788735).

The spelling of 21571223 in words is "twenty-one million, five hundred seventy-one thousand, two hundred twenty-three".