21055103 has 4 divisors (see below), whose sum is σ = 21091560. Its totient is φ = 21018648.

The previous prime is 21055087. The next prime is 21055123. The reversal of 21055103 is 30155012.

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 21055103 - 2⁴ = 21055087 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21055123) 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, 17348 + ... + 18521.

It is an arithmetic number, because the mean of its divisors is an integer number (5272890).

Almost surely, 2^21055103 is an apocalyptic number.

21055103 is a deficient number, since it is larger than the sum of its proper divisors (36457).

21055103 is an equidigital number, since it uses as much as digits as its factorization.

21055103 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 36456.

The product of its (nonzero) digits is 150, while the sum is 17.

The square root of 21055103 is about 4588.5839863731. The cubic root of 21055103 is about 276.1335164057.

Subtracting 21055103 from its reverse (30155012), we obtain a palindrome (9099909).

The spelling of 21055103 in words is "twenty-one million, fifty-five thousand, one hundred three".