21106603 has 6 divisors (see below), whose sum is σ = 24552636. Its totient is φ = 18091332.

The previous prime is 21106583. The next prime is 21106607. The reversal of 21106603 is 30660112.

It is a de Polignac number, because none of the positive numbers 2^k-21106603 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21106607) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 215325 + ... + 215422.

It is an arithmetic number, because the mean of its divisors is an integer number (4092106).

Almost surely, 2^21106603 is an apocalyptic number.

21106603 is a deficient number, since it is larger than the sum of its proper divisors (3446033).

21106603 is an equidigital number, since it uses as much as digits as its factorization.

21106603 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 430761 (or 430754 counting only the distinct ones).

The product of its (nonzero) digits is 216, while the sum is 19.

The square root of 21106603 is about 4594.1923120392. The cubic root of 21106603 is about 276.3584705375.

Adding to 21106603 its reverse (30660112), we get a palindrome (51766715).

The spelling of 21106603 in words is "twenty-one million, one hundred six thousand, six hundred three".