21115227 has 18 divisors (see below), whose sum is σ = 32836788. Its totient is φ = 12034008.

The previous prime is 21115189. The next prime is 21115229. The reversal of 21115227 is 72251112.

It is not a de Polignac number, because 21115227 - 2⁸ = 21114971 is a prime.

It is a super-2 number, since 2×21115227² = 891705622523058, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is not an unprimeable number, because it can be changed into a prime (21115229) 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 17 ways as a sum of consecutive naturals, for example, 55524 + ... + 55902.

It is an arithmetic number, because the mean of its divisors is an integer number (1824266).

Almost surely, 2^21115227 is an apocalyptic number.

21115227 is a deficient number, since it is larger than the sum of its proper divisors (11721561).

21115227 is an frugal number, since it uses more digits than its factorization.

21115227 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 775 (or 389 counting only the distinct ones).

The product of its digits is 280, while the sum is 21.

The square root of 21115227 is about 4595.1307924802. The cubic root of 21115227 is about 276.3961047465.

Adding to 21115227 its reverse (72251112), we get a palindrome (93366339).

The spelling of 21115227 in words is "twenty-one million, one hundred fifteen thousand, two hundred twenty-seven".