1261217669 has 2 divisors, whose sum is σ = 1261217670. Its totient is φ = 1261217668.

The previous prime is 1261217653. The next prime is 1261217677. The reversal of 1261217669 is 9667121621.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1200969025 + 60248644 = 34655^2 + 7762^2 .

It is a cyclic number.

It is not a de Polignac number, because 1261217669 - 2⁴ = 1261217653 is a prime.

It is a super-2 number, since 2×1261217669² = 3181340017195587122, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1261210669) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 630608834 + 630608835.

It is an arithmetic number, because the mean of its divisors is an integer number (630608835).

Almost surely, 2^1261217669 is an apocalyptic number.

It is an amenable number.

1261217669 is a deficient number, since it is larger than the sum of its proper divisors (1).

1261217669 is an equidigital number, since it uses as much as digits as its factorization.

1261217669 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 54432, while the sum is 41.

The square root of 1261217669 is about 35513.6265256028. The cubic root of 1261217669 is about 1080.4301181742.

The spelling of 1261217669 in words is "one billion, two hundred sixty-one million, two hundred seventeen thousand, six hundred sixty-nine".