7172216561 has 2 divisors, whose sum is σ = 7172216562. Its totient is φ = 7172216560.

The previous prime is 7172216537. The next prime is 7172216599. The reversal of 7172216561 is 1656122717.

It is an a-pointer prime, because the next prime (7172216599) can be obtained adding 7172216561 to its sum of digits (38).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 5143614961 + 2028601600 = 71719^2 + 45040^2 .

It is a cyclic number.

It is not a de Polignac number, because 7172216561 - 2¹⁰ = 7172215537 is a prime.

It is not a weakly prime, because it can be changed into another prime (7172216531) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3586108280 + 3586108281.

It is an arithmetic number, because the mean of its divisors is an integer number (3586108281).

Almost surely, 2^7172216561 is an apocalyptic number.

It is an amenable number.

7172216561 is a deficient number, since it is larger than the sum of its proper divisors (1).

7172216561 is an equidigital number, since it uses as much as digits as its factorization.

7172216561 is an evil number, because the sum of its binary digits is even.

The product of its digits is 35280, while the sum is 38.

The square root of 7172216561 is about 84688.9400158014. The cubic root of 7172216561 is about 1928.4918068697.

The spelling of 7172216561 in words is "seven billion, one hundred seventy-two million, two hundred sixteen thousand, five hundred sixty-one".