21609103 has 4 divisors (see below), whose sum is σ = 21800448. Its totient is φ = 21417760.

The previous prime is 21609101. The next prime is 21609109. The reversal of 21609103 is 30190612.

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 21609103 - 2¹ = 21609101 is a prime.

It is a Smith number, since the sum of its digits (22) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21609101) 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, 95503 + ... + 95728.

It is an arithmetic number, because the mean of its divisors is an integer number (5450112).

Almost surely, 2^21609103 is an apocalyptic number.

21609103 is a deficient number, since it is larger than the sum of its proper divisors (191345).

21609103 is a wasteful number, since it uses less digits than its factorization.

21609103 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 191344.

The product of its (nonzero) digits is 324, while the sum is 22.

The square root of 21609103 is about 4648.5592391622. The cubic root of 21609103 is about 278.5344470992.

Adding to 21609103 its reverse (30190612), we get a palindrome (51799715).

It can be divided in two parts, 21609 and 103, that added together give a palindrome (21712).

The spelling of 21609103 in words is "twenty-one million, six hundred nine thousand, one hundred three".