21030320 has 40 divisors (see below), whose sum is σ = 49178400. Its totient is φ = 8363520.

The previous prime is 21030313. The next prime is 21030329. The reversal of 21030320 is 2303012.

It is a tau number, because it is divible by the number of its divisors (40).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21030329) 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, 15260 + ... + 16580.

It is an arithmetic number, because the mean of its divisors is an integer number (1229460).

Almost surely, 2^21030320 is an apocalyptic number.

21030320 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21030320 is an abundant number, since it is smaller than the sum of its proper divisors (28148080).

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

21030320 is a wasteful number, since it uses less digits than its factorization.

21030320 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1533 (or 1527 counting only the distinct ones).

The product of its (nonzero) digits is 36, while the sum is 11.

The square root of 21030320 is about 4585.8826849365. The cubic root of 21030320 is about 276.0251324870.

Adding to 21030320 its reverse (2303012), we get a palindrome (23333332).

The spelling of 21030320 in words is "twenty-one million, thirty thousand, three hundred twenty".