21235040 has 96 divisors (see below), whose sum is σ = 54813024. Its totient is φ = 7741440.

The previous prime is 21235037. The next prime is 21235051. The reversal of 21235040 is 4053212.

It is a Harshad number since it is a multiple of its sum of digits (17).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 100535 + ... + 100745.

It is an arithmetic number, because the mean of its divisors is an integer number (570969).

Almost surely, 2^21235040 is an apocalyptic number.

21235040 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 21235040, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27406512).

21235040 is an abundant number, since it is smaller than the sum of its proper divisors (33577984).

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

21235040 is a wasteful number, since it uses less digits than its factorization.

21235040 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 280 (or 272 counting only the distinct ones).

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

The square root of 21235040 is about 4608.1493031368. The cubic root of 21235040 is about 276.9178989219.

Adding to 21235040 its reverse (4053212), we get a palindrome (25288252).

The spelling of 21235040 in words is "twenty-one million, two hundred thirty-five thousand, forty".