21405103 has 4 divisors (see below), whose sum is σ = 22143240. Its totient is φ = 20666968.

The previous prime is 21405067. The next prime is 21405113. The reversal of 21405103 is 30150412.

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 21405103 - 2¹⁷ = 21274031 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21405113) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 369025 + ... + 369082.

It is an arithmetic number, because the mean of its divisors is an integer number (5535810).

Almost surely, 2^21405103 is an apocalyptic number.

21405103 is a deficient number, since it is larger than the sum of its proper divisors (738137).

21405103 is an equidigital number, since it uses as much as digits as its factorization.

21405103 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 738136.

The product of its (nonzero) digits is 120, while the sum is 16.

The square root of 21405103 is about 4626.5649244337. The cubic root of 21405103 is about 277.6551760409.

Adding to 21405103 its reverse (30150412), we get a palindrome (51555515).

The spelling of 21405103 in words is "twenty-one million, four hundred five thousand, one hundred three".