21441240 has 64 divisors (see below), whose sum is σ = 71474400. Its totient is φ = 5717376.

The previous prime is 21441239. The next prime is 21441247. The reversal of 21441240 is 4214412.

21441240 is a `hidden beast` number, since 214 + 412 + 40 = 666.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21441247) 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, 8847 + ... + 11006.

Almost surely, 2^21441240 is an apocalyptic number.

21441240 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21441240 is an abundant number, since it is smaller than the sum of its proper divisors (50033160).

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

21441240 is a wasteful number, since it uses less digits than its factorization.

21441240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19873 (or 19863 counting only the distinct ones).

The product of its (nonzero) digits is 256, while the sum is 18.

The square root of 21441240 is about 4630.4686587861. The cubic root of 21441240 is about 277.8113379304.

Adding to 21441240 its reverse (4214412), we get a palindrome (25655652).

The spelling of 21441240 in words is "twenty-one million, four hundred forty-one thousand, two hundred forty".