42218521 has 4 divisors (see below), whose sum is σ = 42257700. Its totient is φ = 42179344.

The previous prime is 42218507. The next prime is 42218537. The reversal of 42218521 is 12581224.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 10634121 + 31584400 = 3261^2 + 5620^2 .

It is a cyclic number.

It is not a de Polignac number, because 42218521 - 2¹⁵ = 42185753 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (42218321) 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, 17926 + ... + 20143.

It is an arithmetic number, because the mean of its divisors is an integer number (10564425).

Almost surely, 2^42218521 is an apocalyptic number.

It is an amenable number.

42218521 is a deficient number, since it is larger than the sum of its proper divisors (39179).

42218521 is a wasteful number, since it uses less digits than its factorization.

42218521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 39178.

The product of its digits is 1280, while the sum is 25.

The square root of 42218521 is about 6497.5780872568. The cubic root of 42218521 is about 348.2044670838.

Adding to 42218521 its reverse (12581224), we get a palindrome (54799745).

The spelling of 42218521 in words is "forty-two million, two hundred eighteen thousand, five hundred twenty-one".