72222121 has 2 divisors, whose sum is σ = 72222122. Its totient is φ = 72222120.

The previous prime is 72222119. The next prime is 72222131. The reversal of 72222121 is 12122227.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 64320400 + 7901721 = 8020^2 + 2811^2 .

It is a cyclic number.

It is not a de Polignac number, because 72222121 - 2¹ = 72222119 is a prime.

Together with 72222119, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (72222131) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 36111060 + 36111061.

It is an arithmetic number, because the mean of its divisors is an integer number (36111061).

Almost surely, 2^72222121 is an apocalyptic number.

It is an amenable number.

72222121 is a deficient number, since it is larger than the sum of its proper divisors (1).

72222121 is an equidigital number, since it uses as much as digits as its factorization.

72222121 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 224, while the sum is 19.

The square root of 72222121 is about 8498.3599005926. The cubic root of 72222121 is about 416.4441312661. Note that the first 3 decimals are identical.

Adding to 72222121 its reverse (12122227), we get a palindrome (84344348).

The spelling of 72222121 in words is "seventy-two million, two hundred twenty-two thousand, one hundred twenty-one".