21010320 has 160 divisors (see below), whose sum is σ = 73923840. Its totient is φ = 5483520.

The previous prime is 21010307. The next prime is 21010321. The reversal of 21010320 is 2301012.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is not an unprimeable number, because it can be changed into a prime (21010321) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 153292 + ... + 153428.

It is an arithmetic number, because the mean of its divisors is an integer number (462024).

Almost surely, 2^21010320 is an apocalyptic number.

21010320 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21010320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36961920).

21010320 is an abundant number, since it is smaller than the sum of its proper divisors (52913520).

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

21010320 is a wasteful number, since it uses less digits than its factorization.

21010320 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 230 (or 218 counting only the distinct ones).

The product of its (nonzero) digits is 12, while the sum is 9.

The square root of 21010320 is about 4583.7015609658. The cubic root of 21010320 is about 275.9376040425.

Adding to 21010320 its reverse (2301012), we get a palindrome (23311332).

The spelling of 21010320 in words is "twenty-one million, ten thousand, three hundred twenty".