21320310 has 96 divisors (see below), whose sum is σ = 59367168. Its totient is φ = 4850560.

The previous prime is 21320297. The next prime is 21320311. The reversal of 21320310 is 1302312.

It is a happy number.

It is a super-2 number, since 2×21320310² = 909111236992200, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21320311) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 402244 + ... + 402296.

It is an arithmetic number, because the mean of its divisors is an integer number (618408).

Almost surely, 2^21320310 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21320310, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29683584).

21320310 is an abundant number, since it is smaller than the sum of its proper divisors (38046858).

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

21320310 is a wasteful number, since it uses less digits than its factorization.

21320310 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 150 (or 97 counting only the distinct ones).

The product of its (nonzero) digits is 36, while the sum is 12.

The square root of 21320310 is about 4617.3921211004. The cubic root of 21320310 is about 277.2880615333.

Adding to 21320310 its reverse (1302312), we get a palindrome (22622622).

The spelling of 21320310 in words is "twenty-one million, three hundred twenty thousand, three hundred ten".