21241240 has 48 divisors (see below), whose sum is σ = 50474880. Its totient is φ = 8043840.

The previous prime is 21241229. The next prime is 21241247. The reversal of 21241240 is 4214212.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21241247) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 13705 + ... + 15175.

It is an arithmetic number, because the mean of its divisors is an integer number (1051560).

Almost surely, 2^21241240 is an apocalyptic number.

21241240 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 21241240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25237440).

21241240 is an abundant number, since it is smaller than the sum of its proper divisors (29233640).

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

21241240 is a wasteful number, since it uses less digits than its factorization.

21241240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1520 (or 1497 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 16.

The square root of 21241240 is about 4608.8219752991. The cubic root of 21241240 is about 276.9448468957.

Adding to 21241240 its reverse (4214212), we get a palindrome (25455452).

It can be divided in two parts, 2124 and 1240, that added together give a square (3364 = 58²).

The spelling of 21241240 in words is "twenty-one million, two hundred forty-one thousand, two hundred forty".