42216521 has 2 divisors, whose sum is σ = 42216522. Its totient is φ = 42216520.

The previous prime is 42216487. The next prime is 42216533. The reversal of 42216521 is 12561224.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 32205625 + 10010896 = 5675^2 + 3164^2 .

It is a cyclic number.

It is not a de Polignac number, because 42216521 - 2¹⁰ = 42215497 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (42216541) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 21108260 + 21108261.

It is an arithmetic number, because the mean of its divisors is an integer number (21108261).

Almost surely, 2^42216521 is an apocalyptic number.

It is an amenable number.

42216521 is a deficient number, since it is larger than the sum of its proper divisors (1).

42216521 is an equidigital number, since it uses as much as digits as its factorization.

42216521 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 960, while the sum is 23.

The square root of 42216521 is about 6497.4241819355. The cubic root of 42216521 is about 348.1989685497.

Adding to 42216521 its reverse (12561224), we get a palindrome (54777745).

The spelling of 42216521 in words is "forty-two million, two hundred sixteen thousand, five hundred twenty-one".