42222221 has 2 divisors, whose sum is σ = 42222222. Its totient is φ = 42222220.

The previous prime is 42222139. The next prime is 42222233. The reversal of 42222221 is 12222224.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 29008996 + 13213225 = 5386^2 + 3635^2 .

It is a cyclic number.

It is not a de Polignac number, because 42222221 - 2¹⁰ = 42221197 is a prime.

It is a nialpdrome in base 10.

It is a zygodrome in base 3.

It is a self number, because there is not a number n which added to its sum of digits gives 42222221.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (42222281) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 21111110 + 21111111.

It is an arithmetic number, because the mean of its divisors is an integer number (21111111).

Almost surely, 2^42222221 is an apocalyptic number.

It is an amenable number.

42222221 is a deficient number, since it is larger than the sum of its proper divisors (1).

42222221 is an equidigital number, since it uses as much as digits as its factorization.

42222221 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 256, while the sum is 17.

The square root of 42222221 is about 6497.8628024913. The cubic root of 42222221 is about 348.2146389141.

Adding to 42222221 its reverse (12222224), we get a palindrome (54444445).

The spelling of 42222221 in words is "forty-two million, two hundred twenty-two thousand, two hundred twenty-one".