21023310 has 128 divisors (see below), whose sum is σ = 66355200. Its totient is φ = 4129920.

The previous prime is 21023309. The next prime is 21023323. The reversal of 21023310 is 1332012.

It is a happy number.

It is a super-2 number, since 2×21023310² = 883959126712200, 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 63 ways as a sum of consecutive naturals, for example, 43651 + ... + 44129.

It is an arithmetic number, because the mean of its divisors is an integer number (518400).

Almost surely, 2^21023310 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21023310, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33177600).

21023310 is an abundant number, since it is smaller than the sum of its proper divisors (45331890).

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

21023310 is a wasteful number, since it uses less digits than its factorization.

21023310 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 526.

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

The square root of 21023310 is about 4585.1183190840. The cubic root of 21023310 is about 275.9944600862.

Adding to 21023310 its reverse (1332012), we get a palindrome (22355322).

The spelling of 21023310 in words is "twenty-one million, twenty-three thousand, three hundred ten".