21101603 has 4 divisors (see below), whose sum is σ = 22019088. Its totient is φ = 20184120.

The previous prime is 21101569. The next prime is 21101617. The reversal of 21101603 is 30610112.

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 21101603 - 2¹⁰ = 21100579 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21101683) 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, 458708 + ... + 458753.

It is an arithmetic number, because the mean of its divisors is an integer number (5504772).

Almost surely, 2^21101603 is an apocalyptic number.

21101603 is a gapful number since it is divisible by the number (23) formed by its first and last digit.

21101603 is a deficient number, since it is larger than the sum of its proper divisors (917485).

21101603 is an equidigital number, since it uses as much as digits as its factorization.

21101603 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 917484.

The product of its (nonzero) digits is 36, while the sum is 14.

The square root of 21101603 is about 4593.6481145164. The cubic root of 21101603 is about 276.3366463801.

Adding to 21101603 its reverse (30610112), we get a palindrome (51711715).

The spelling of 21101603 in words is "twenty-one million, one hundred one thousand, six hundred three".