1221175171609 has 2 divisors, whose sum is σ = 1221175171610. Its totient is φ = 1221175171608.

The previous prime is 1221175171561. The next prime is 1221175171613. The reversal of 1221175171609 is 9061715711221.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 760683997584 + 460491174025 = 872172^2 + 678595^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1221175171609 is a prime.

It is not a weakly prime, because it can be changed into another prime (1221175171639) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 610587585804 + 610587585805.

It is an arithmetic number, because the mean of its divisors is an integer number (610587585805).

Almost surely, 2^{1221175171609} is an apocalyptic number.

It is an amenable number.

1221175171609 is a deficient number, since it is larger than the sum of its proper divisors (1).

1221175171609 is an equidigital number, since it uses as much as digits as its factorization.

1221175171609 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 52920, while the sum is 43.

The spelling of 1221175171609 in words is "one trillion, two hundred twenty-one billion, one hundred seventy-five million, one hundred seventy-one thousand, six hundred nine".