7218121 has 2 divisors, whose sum is σ = 7218122. Its totient is φ = 7218120.

The previous prime is 7218083. The next prime is 7218139. The reversal of 7218121 is 1218127.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 7182400 + 35721 = 2680^2 + 189^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-7218121 is a prime.

It is an alternating number because its digits alternate between odd and even.

It is a junction number, because it is equal to n+sod(n) for n = 7218092 and 7218101.

It is not a weakly prime, because it can be changed into another prime (7218161) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3609060 + 3609061.

It is an arithmetic number, because the mean of its divisors is an integer number (3609061).

Almost surely, 2^7218121 is an apocalyptic number.

It is an amenable number.

7218121 is a deficient number, since it is larger than the sum of its proper divisors (1).

7218121 is an equidigital number, since it uses as much as digits as its factorization.

7218121 is an evil number, because the sum of its binary digits is even.

The product of its digits is 224, while the sum is 22.

The square root of 7218121 is about 2686.6561000619. The cubic root of 7218121 is about 193.2597378093.

It can be divided in two parts, 7218 and 121, that multiplied together give a palindrome (873378).

The spelling of 7218121 in words is "seven million, two hundred eighteen thousand, one hundred twenty-one".