21102213 has 16 divisors (see below), whose sum is σ = 30897216. Its totient is φ = 12704640.

The previous prime is 21102209. The next prime is 21102239. The reversal of 21102213 is 31220112.

It is not a de Polignac number, because 21102213 - 2² = 21102209 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21102113) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3145 + ... + 7217.

It is an arithmetic number, because the mean of its divisors is an integer number (1931076).

Almost surely, 2^21102213 is an apocalyptic number.

It is an amenable number.

21102213 is a deficient number, since it is larger than the sum of its proper divisors (9795003).

21102213 is a wasteful number, since it uses less digits than its factorization.

21102213 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4244.

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

The square root of 21102213 is about 4593.7145100670. The cubic root of 21102213 is about 276.3393091120.

Adding to 21102213 its reverse (31220112), we get a palindrome (52322325).

The spelling of 21102213 in words is "twenty-one million, one hundred two thousand, two hundred thirteen".