21115456 has 42 divisors (see below), whose sum is σ = 43242738. Its totient is φ = 10229760.

The previous prime is 21115453. The next prime is 21115511. The reversal of 21115456 is 65451112.

It is a happy number.

It can be written as a sum of positive squares in 3 ways, for example, as 14561856 + 6553600 = 3816^2 + 2560^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21115456.

It is not an unprimeable number, because it can be changed into a prime (21115453) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 87496 + ... + 87736.

It is an arithmetic number, because the mean of its divisors is an integer number (1029589).

Almost surely, 2^21115456 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21115456, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (21621369).

21115456 is an abundant number, since it is smaller than the sum of its proper divisors (22127282).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21115456 is an equidigital number, since it uses as much as digits as its factorization.

21115456 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 327 (or 280 counting only the distinct ones).

The product of its digits is 1200, while the sum is 25.

The square root of 21115456 is about 4595.1557100930. The cubic root of 21115456 is about 276.3971039382.

Adding to 21115456 its reverse (65451112), we get a palindrome (86566568).

The spelling of 21115456 in words is "twenty-one million, one hundred fifteen thousand, four hundred fifty-six".