21440242 has 8 divisors (see below), whose sum is σ = 33029676. Its totient is φ = 10430352.

The previous prime is 21440239. The next prime is 21440257. The reversal of 21440242 is 24204412.

It can be written as a sum of positive squares in 2 ways, for example, as 14830201 + 6610041 = 3851^2 + 2571^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 144793 + ... + 144940.

Almost surely, 2^21440242 is an apocalyptic number.

21440242 is a deficient number, since it is larger than the sum of its proper divisors (11589434).

21440242 is a wasteful number, since it uses less digits than its factorization.

21440242 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 289772.

The product of its (nonzero) digits is 512, while the sum is 19.

The square root of 21440242 is about 4630.3608930622. The cubic root of 21440242 is about 277.8070275451.

Adding to 21440242 its reverse (24204412), we get a palindrome (45644654).

The spelling of 21440242 in words is "twenty-one million, four hundred forty thousand, two hundred forty-two".