21103547 has 4 divisors (see below), whose sum is σ = 22214280. Its totient is φ = 19992816.

The previous prime is 21103531. The next prime is 21103549. The reversal of 21103547 is 74530112.

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 21103547 - 2⁴ = 21103531 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21103549) 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, 555338 + ... + 555375.

It is an arithmetic number, because the mean of its divisors is an integer number (5553570).

Almost surely, 2^21103547 is an apocalyptic number.

21103547 is a deficient number, since it is larger than the sum of its proper divisors (1110733).

21103547 is a wasteful number, since it uses less digits than its factorization.

21103547 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1110732.

The product of its (nonzero) digits is 840, while the sum is 23.

The square root of 21103547 is about 4593.8597061730. The cubic root of 21103547 is about 276.3451320221.

Adding to 21103547 its reverse (74530112), we get a palindrome (95633659).

The spelling of 21103547 in words is "twenty-one million, one hundred three thousand, five hundred forty-seven".