21008227 has 4 divisors (see below), whose sum is σ = 21021760. Its totient is φ = 20994696.

The previous prime is 21008219. The next prime is 21008237. The reversal of 21008227 is 72280012.

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 21008227 - 2³ = 21008219 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21008198 and 21008207.

It is not an unprimeable number, because it can be changed into a prime (21008237) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4083 + ... + 7660.

It is an arithmetic number, because the mean of its divisors is an integer number (5255440).

Almost surely, 2^21008227 is an apocalyptic number.

21008227 is a deficient number, since it is larger than the sum of its proper divisors (13533).

21008227 is a wasteful number, since it uses less digits than its factorization.

21008227 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13532.

The product of its (nonzero) digits is 448, while the sum is 22.

The square root of 21008227 is about 4583.4732463493. The cubic root of 21008227 is about 275.9284409807.

Adding to 21008227 its reverse (72280012), we get a palindrome (93288239).

The spelling of 21008227 in words is "twenty-one million, eight thousand, two hundred twenty-seven".