866763831999661 has 2 divisors, whose sum is σ = 866763831999662. Its totient is φ = 866763831999660.

The previous prime is 866763831999589. The next prime is 866763831999677. The reversal of 866763831999661 is 166999138367668.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 447550737606025 + 419213094393636 = 21155395^2 + 20474694^2 .

It is a cyclic number.

It is not a de Polignac number, because 866763831999661 - 2¹³ = 866763831991469 is a prime.

It is a super-2 number, since 2×866763831999661² (a number of 31 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (866763831969661) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 433381915999830 + 433381915999831.

It is an arithmetic number, because the mean of its divisors is an integer number (433381915999831).

Almost surely, 2^{866763831999661} is an apocalyptic number.

It is an amenable number.

866763831999661 is a deficient number, since it is larger than the sum of its proper divisors (1).

866763831999661 is an equidigital number, since it uses as much as digits as its factorization.

866763831999661 is an evil number, because the sum of its binary digits is even.

The product of its digits is 22856214528, while the sum is 88.

The spelling of 866763831999661 in words is "eight hundred sixty-six trillion, seven hundred sixty-three billion, eight hundred thirty-one million, nine hundred ninety-nine thousand, six hundred sixty-one".