21018244 has 12 divisors (see below), whose sum is σ = 39611404. Its totient is φ = 9700704.

The previous prime is 21018241. The next prime is 21018247. The reversal of 21018244 is 44281012.

It is an interprime number because it is at equal distance from previous prime (21018241) and next prime (21018247).

It can be written as a sum of positive squares in 2 ways, for example, as 10969344 + 10048900 = 3312^2 + 3170^2 .

It is not an unprimeable number, because it can be changed into a prime (21018241) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 202047 + ... + 202150.

Almost surely, 2^21018244 is an apocalyptic number.

It is an amenable number.

21018244 is a deficient number, since it is larger than the sum of its proper divisors (18593160).

21018244 is a wasteful number, since it uses less digits than its factorization.

21018244 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 404214 (or 404212 counting only the distinct ones).

The product of its (nonzero) digits is 512, while the sum is 22.

The square root of 21018244 is about 4584.5658464025. The cubic root of 21018244 is about 275.9722894535.

Adding to 21018244 its reverse (44281012), we get a palindrome (65299256).

The spelling of 21018244 in words is "twenty-one million, eighteen thousand, two hundred forty-four".