21035240 has 64 divisors (see below), whose sum is σ = 49617360. Its totient is φ = 8017920.

The previous prime is 21035233. The next prime is 21035249. The reversal of 21035240 is 4253012.

It can be written as a sum of positive squares in 8 ways, for example, as 4502884 + 16532356 = 2122^2 + 4066^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21035249) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 90164 + ... + 90396.

Almost surely, 2^21035240 is an apocalyptic number.

21035240 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 21035240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24808680).

21035240 is an abundant number, since it is smaller than the sum of its proper divisors (28582120).

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

21035240 is a wasteful number, since it uses less digits than its factorization.

21035240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 342 (or 338 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 17.

The square root of 21035240 is about 4586.4190824651. The cubic root of 21035240 is about 276.0466559788.

Adding to 21035240 its reverse (4253012), we get a palindrome (25288252).

The spelling of 21035240 in words is "twenty-one million, thirty-five thousand, two hundred forty".