21280242 has 16 divisors (see below), whose sum is σ = 43364160. Its totient is φ = 6959472.

The previous prime is 21280241. The next prime is 21280253. The reversal of 21280242 is 24208212.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (21280241) 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 7 ways as a sum of consecutive naturals, for example, 33142 + ... + 33777.

It is an arithmetic number, because the mean of its divisors is an integer number (2710260).

Almost surely, 2^21280242 is an apocalyptic number.

21280242 is an abundant number, since it is smaller than the sum of its proper divisors (22083918).

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

21280242 is a wasteful number, since it uses less digits than its factorization.

21280242 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 66977.

The product of its (nonzero) digits is 512, while the sum is 21.

The square root of 21280242 is about 4613.0512678703. The cubic root of 21280242 is about 277.1142469036.

Adding to 21280242 its reverse (24208212), we get a palindrome (45488454).

The spelling of 21280242 in words is "twenty-one million, two hundred eighty thousand, two hundred forty-two".