21212110 has 16 divisors (see below), whose sum is σ = 38298096. Its totient is φ = 8459008.

The previous prime is 21212101. The next prime is 21212111. The reversal of 21212110 is 1121212.

It is a super-3 number, since 3×21212110³ (a number of 23 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Harshad number since it is a multiple of its sum of digits (10).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21212111) 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, 414 + ... + 6526.

It is an arithmetic number, because the mean of its divisors is an integer number (2393631).

Almost surely, 2^21212110 is an apocalyptic number.

21212110 is a deficient number, since it is larger than the sum of its proper divisors (17085986).

21212110 is a wasteful number, since it uses less digits than its factorization.

21212110 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6467.

The product of its (nonzero) digits is 8, while the sum is 10.

The square root of 21212110 is about 4605.6606475076. The cubic root of 21212110 is about 276.8181892861.

Adding to 21212110 its reverse (1121212), we get a palindrome (22333322).

The spelling of 21212110 in words is "twenty-one million, two hundred twelve thousand, one hundred ten".