4042121221 has 2 divisors, whose sum is σ = 4042121222. Its totient is φ = 4042121220.

The previous prime is 4042121219. The next prime is 4042121227. The reversal of 4042121221 is 1221212404.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 3674056996 + 368064225 = 60614^2 + 19185^2 .

It is a cyclic number.

It is not a de Polignac number, because 4042121221 - 2¹ = 4042121219 is a prime.

Together with 4042121219, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (4042121227) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2021060610 + 2021060611.

It is an arithmetic number, because the mean of its divisors is an integer number (2021060611).

Almost surely, 2^4042121221 is an apocalyptic number.

It is an amenable number.

4042121221 is a deficient number, since it is larger than the sum of its proper divisors (1).

4042121221 is an equidigital number, since it uses as much as digits as its factorization.

4042121221 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 256, while the sum is 19.

The square root of 4042121221 is about 63577.6786380252. The cubic root of 4042121221 is about 1592.9535467261.

Adding to 4042121221 its reverse (1221212404), we get a palindrome (5263333625).

The spelling of 4042121221 in words is "four billion, forty-two million, one hundred twenty-one thousand, two hundred twenty-one".