7772221 has 2 divisors, whose sum is σ = 7772222. Its totient is φ = 7772220.

The previous prime is 7772209. The next prime is 7772251. The reversal of 7772221 is 1222777.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 6320196 + 1452025 = 2514^2 + 1205^2 .

It is an emirp because it is prime and its reverse (1222777) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 7772221 - 2⁵ = 7772189 is a prime.

It is a nialpdrome in base 10.

It is a self number, because there is not a number n which added to its sum of digits gives 7772221.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (7772251) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3886110 + 3886111.

It is an arithmetic number, because the mean of its divisors is an integer number (3886111).

Almost surely, 2^7772221 is an apocalyptic number.

It is an amenable number.

7772221 is a deficient number, since it is larger than the sum of its proper divisors (1).

7772221 is an equidigital number, since it uses as much as digits as its factorization.

7772221 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2744, while the sum is 28.

The square root of 7772221 is about 2787.8703341440. The cubic root of 7772221 is about 198.0835361554.

Adding to 7772221 its reverse (1222777), we get a palindrome (8994998).

The spelling of 7772221 in words is "seven million, seven hundred seventy-two thousand, two hundred twenty-one".