21103213 has 12 divisors (see below), whose sum is σ = 22827168. Its totient is φ = 19471760.

The previous prime is 21103211. The next prime is 21103217. The reversal of 21103213 is 31230112.

It is not a de Polignac number, because 21103213 - 2¹ = 21103211 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21103193 and 21103202.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21103211) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 18798 + ... + 19888.

It is an arithmetic number, because the mean of its divisors is an integer number (1902264).

Almost surely, 2^21103213 is an apocalyptic number.

21103213 is a gapful number since it is divisible by the number (23) formed by its first and last digit.

It is an amenable number.

21103213 is a deficient number, since it is larger than the sum of its proper divisors (1723955).

21103213 is a wasteful number, since it uses less digits than its factorization.

21103213 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1172 (or 1143 counting only the distinct ones).

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

The square root of 21103213 is about 4593.8233531558. The cubic root of 21103213 is about 276.3436741351.

Adding to 21103213 its reverse (31230112), we get a palindrome (52333325).

It can be divided in two parts, 21103 and 213, that added together give a square (21316 = 146²).

The spelling of 21103213 in words is "twenty-one million, one hundred three thousand, two hundred thirteen".