21102221 has 8 divisors (see below), whose sum is σ = 24145920. Its totient is φ = 18065808.

The previous prime is 21102209. The next prime is 21102239. The reversal of 21102221 is 12220112.

It is a happy number.

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 21102221 - 2¹⁴ = 21085837 is a prime.

It is a super-2 number, since 2×21102221² = 890607462265682, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21102251) 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, 7775 + ... + 10131.

It is an arithmetic number, because the mean of its divisors is an integer number (3018240).

Almost surely, 2^21102221 is an apocalyptic number.

It is an amenable number.

21102221 is a deficient number, since it is larger than the sum of its proper divisors (3043699).

21102221 is a wasteful number, since it uses less digits than its factorization.

21102221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3643.

The product of its (nonzero) digits is 16, while the sum is 11.

The square root of 21102221 is about 4593.7153808219. The cubic root of 21102221 is about 276.3393440327.

Adding to 21102221 its reverse (12220112), we get a palindrome (33322333).

The spelling of 21102221 in words is "twenty-one million, one hundred two thousand, two hundred twenty-one".