21552231 has 4 divisors (see below), whose sum is σ = 28736312. Its totient is φ = 14368152.

The previous prime is 21552221. The next prime is 21552233. The reversal of 21552231 is 13225512.

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

It is not a de Polignac number, because 21552231 - 2¹¹ = 21550183 is a prime.

It is a super-2 number, since 2×21552231² = 928997322154722, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21552198 and 21552207.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21552233) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3592036 + ... + 3592041.

It is an arithmetic number, because the mean of its divisors is an integer number (7184078).

Almost surely, 2^21552231 is an apocalyptic number.

21552231 is a deficient number, since it is larger than the sum of its proper divisors (7184081).

21552231 is an equidigital number, since it uses as much as digits as its factorization.

21552231 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7184080.

The product of its digits is 600, while the sum is 21.

The square root of 21552231 is about 4642.4380448208. The cubic root of 21552231 is about 278.2898784355.

Adding to 21552231 its reverse (13225512), we get a palindrome (34777743).

The spelling of 21552231 in words is "twenty-one million, five hundred fifty-two thousand, two hundred thirty-one".