21303040 has 144 divisors (see below), whose sum is σ = 59603040. Its totient is φ = 7208960.

The previous prime is 21303031. The next prime is 21303041. The reversal of 21303040 is 4030312.

21303040 = T₅₉ + T₆₀ + ... + T₅₀₃.

It is a self number, because there is not a number n which added to its sum of digits gives 21303040.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21303041) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 239316 + ... + 239404.

It is an arithmetic number, because the mean of its divisors is an integer number (413910).

Almost surely, 2^21303040 is an apocalyptic number.

21303040 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 21303040, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29801520).

21303040 is an abundant number, since it is smaller than the sum of its proper divisors (38300000).

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

21303040 is a wasteful number, since it uses less digits than its factorization.

21303040 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 138 (or 124 counting only the distinct ones).

The product of its (nonzero) digits is 72, while the sum is 13.

The square root of 21303040 is about 4615.5216389916. The cubic root of 21303040 is about 277.2131711524.

Adding to 21303040 its reverse (4030312), we get a palindrome (25333352).

The spelling of 21303040 in words is "twenty-one million, three hundred three thousand, forty".