21212310 has 64 divisors (see below), whose sum is σ = 58931712. Its totient is φ = 4786176.

The previous prime is 21212297. The next prime is 21212353. The reversal of 21212310 is 1321212.

It is a super-2 number, since 2×21212310² = 899924191072200, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 16822 + ... + 18038.

It is an arithmetic number, because the mean of its divisors is an integer number (920808).

Almost surely, 2^21212310 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21212310, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29465856).

21212310 is an abundant number, since it is smaller than the sum of its proper divisors (37719402).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21212310 is a wasteful number, since it uses less digits than its factorization.

21212310 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1317.

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

The square root of 21212310 is about 4605.6823598681. The cubic root of 21212310 is about 276.8190592838.

Adding to 21212310 its reverse (1321212), we get a palindrome (22533522).

The spelling of 21212310 in words is "twenty-one million, two hundred twelve thousand, three hundred ten".