21241818 has 32 divisors (see below), whose sum is σ = 50836800. Its totient is φ = 6535728.

The previous prime is 21241799. The next prime is 21241819. The reversal of 21241818 is 81814212.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a junction number, because it is equal to n+sod(n) for n = 21241791 and 21241800.

It is not an unprimeable number, because it can be changed into a prime (21241819) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 14428 + ... + 15831.

It is an arithmetic number, because the mean of its divisors is an integer number (1588650).

Almost surely, 2^21241818 is an apocalyptic number.

21241818 is an abundant number, since it is smaller than the sum of its proper divisors (29594982).

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

21241818 is a wasteful number, since it uses less digits than its factorization.

21241818 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 30283 (or 30277 counting only the distinct ones).

The product of its digits is 1024, while the sum is 27.

The square root of 21241818 is about 4608.8846807010. The cubic root of 21241818 is about 276.9473588751.

The spelling of 21241818 in words is "twenty-one million, two hundred forty-one thousand, eight hundred eighteen".