7221215257 has 2 divisors, whose sum is σ = 7221215258. Its totient is φ = 7221215256.

The previous prime is 7221215231. The next prime is 7221215279. The reversal of 7221215257 is 7525121227.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 7078866496 + 142348761 = 84136^2 + 11931^2 .

It is a cyclic number.

It is not a de Polignac number, because 7221215257 - 2¹⁵ = 7221182489 is a prime.

It is not a weakly prime, because it can be changed into another prime (7221215207) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3610607628 + 3610607629.

It is an arithmetic number, because the mean of its divisors is an integer number (3610607629).

Almost surely, 2^7221215257 is an apocalyptic number.

It is an amenable number.

7221215257 is a deficient number, since it is larger than the sum of its proper divisors (1).

7221215257 is an equidigital number, since it uses as much as digits as its factorization.

7221215257 is an evil number, because the sum of its binary digits is even.

The product of its digits is 19600, while the sum is 34.

The square root of 7221215257 is about 84977.7338895313. The cubic root of 7221215257 is about 1932.8734932888.

The spelling of 7221215257 in words is "seven billion, two hundred twenty-one million, two hundred fifteen thousand, two hundred fifty-seven".