21103056 has 60 divisors (see below), whose sum is σ = 63607908. Its totient is φ = 6492672.

The previous prime is 21103051. The next prime is 21103073. The reversal of 21103056 is 65030112.

It can be written as a sum of positive squares in 2 ways, for example, as 4161600 + 16941456 = 2040^2 + 4116^2 .

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21103051) 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 11 ways as a sum of consecutive naturals, for example, 3765 + ... + 7508.

Almost surely, 2^21103056 is an apocalyptic number.

21103056 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

It is an amenable number.

21103056 is an abundant number, since it is smaller than the sum of its proper divisors (42504852).

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

21103056 is a wasteful number, since it uses less digits than its factorization.

21103056 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11300 (or 11291 counting only the distinct ones).

The product of its (nonzero) digits is 180, while the sum is 18.

The square root of 21103056 is about 4593.8062649616. The cubic root of 21103056 is about 276.3429888356.

Adding to 21103056 its reverse (65030112), we get a palindrome (86133168).

The spelling of 21103056 in words is "twenty-one million, one hundred three thousand, fifty-six".