1221175171561 has 2 divisors, whose sum is σ = 1221175171562. Its totient is φ = 1221175171560.

The previous prime is 1221175171547. The next prime is 1221175171609. The reversal of 1221175171561 is 1651715711221.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 951327129600 + 269848041961 = 975360^2 + 519469^2 .

It is a cyclic number.

It is not a de Polignac number, because 1221175171561 - 2¹⁵ = 1221175138793 is a prime.

It is not a weakly prime, because it can be changed into another prime (1221175171501) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 610587585780 + 610587585781.

It is an arithmetic number, because the mean of its divisors is an integer number (610587585781).

Almost surely, 2^{1221175171561} is an apocalyptic number.

It is an amenable number.

1221175171561 is a deficient number, since it is larger than the sum of its proper divisors (1).

1221175171561 is an equidigital number, since it uses as much as digits as its factorization.

1221175171561 is an evil number, because the sum of its binary digits is even.

The product of its digits is 29400, while the sum is 40.

The spelling of 1221175171561 in words is "one trillion, two hundred twenty-one billion, one hundred seventy-five million, one hundred seventy-one thousand, five hundred sixty-one".