21552171 has 4 divisors (see below), whose sum is σ = 28736232. Its totient is φ = 14368112.

The previous prime is 21552143. The next prime is 21552197. The reversal of 21552171 is 17125512.

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 21552171 - 2⁷ = 21552043 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21552131) 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, 3592026 + ... + 3592031.

It is an arithmetic number, because the mean of its divisors is an integer number (7184058).

Almost surely, 2^21552171 is an apocalyptic number.

21552171 is a deficient number, since it is larger than the sum of its proper divisors (7184061).

21552171 is an equidigital number, since it uses as much as digits as its factorization.

21552171 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7184060.

The product of its digits is 700, while the sum is 24.

The square root of 21552171 is about 4642.4315826946. The cubic root of 21552171 is about 278.2896201883.

Adding to 21552171 its reverse (17125512), we get a palindrome (38677683).

The spelling of 21552171 in words is "twenty-one million, five hundred fifty-two thousand, one hundred seventy-one".