21212103 has 8 divisors (see below), whose sum is σ = 30854016. Its totient is φ = 12855800.

The previous prime is 21212101. The next prime is 21212111. The reversal of 21212103 is 30121212.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21212103 - 2¹ = 21212101 is a prime.

It is a super-3 number, since 3×21212103³ (a number of 23 digits) contains 333 as substring.

It is an alternating number because its digits alternate between even and odd.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21212101) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 321363 + ... + 321428.

It is an arithmetic number, because the mean of its divisors is an integer number (3856752).

Almost surely, 2^21212103 is an apocalyptic number.

21212103 is a deficient number, since it is larger than the sum of its proper divisors (9641913).

21212103 is a wasteful number, since it uses less digits than its factorization.

21212103 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 642805.

The product of its (nonzero) digits is 24, while the sum is 12.

The square root of 21212103 is about 4605.6598875731. The cubic root of 21212103 is about 276.8181588360.

Adding to 21212103 its reverse (30121212), we get a palindrome (51333315).

It can be divided in two parts, 2121 and 2103, that added together give a palindrome (4224).

The spelling of 21212103 in words is "twenty-one million, two hundred twelve thousand, one hundred three".