21213103 has 4 divisors (see below), whose sum is σ = 21262528. Its totient is φ = 21163680.

The previous prime is 21213097. The next prime is 21213109. The reversal of 21213103 is 30131212.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (21213097) and next prime (21213109).

It is a cyclic number.

It is not a de Polignac number, because 21213103 - 2⁹ = 21212591 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21213109) 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, 24063 + ... + 24928.

It is an arithmetic number, because the mean of its divisors is an integer number (5315632).

Almost surely, 2^21213103 is an apocalyptic number.

21213103 is a deficient number, since it is larger than the sum of its proper divisors (49425).

21213103 is an equidigital number, since it uses as much as digits as its factorization.

21213103 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 49424.

The product of its (nonzero) digits is 36, while the sum is 13.

The square root of 21213103 is about 4605.7684483699. The cubic root of 21213103 is about 276.8225087711.

Adding to 21213103 its reverse (30131212), we get a palindrome (51344315).

It can be divided in two parts, 21213 and 103, that added together give a square (21316 = 146²).

The spelling of 21213103 in words is "twenty-one million, two hundred thirteen thousand, one hundred three".