866761067521381 has 2 divisors, whose sum is σ = 866761067521382. Its totient is φ = 866761067521380.

The previous prime is 866761067521373. The next prime is 866761067521387. The reversal of 866761067521381 is 183125760167668.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 446176481952100 + 420584585569281 = 21122890^2 + 20508159^2 .

It is a cyclic number.

It is not a de Polignac number, because 866761067521381 - 2³ = 866761067521373 is a prime.

It is a super-2 number, since 2×866761067521381² (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 (866761067521387) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 433380533760690 + 433380533760691.

It is an arithmetic number, because the mean of its divisors is an integer number (433380533760691).

Almost surely, 2^{866761067521381} is an apocalyptic number.

It is an amenable number.

866761067521381 is a deficient number, since it is larger than the sum of its proper divisors (1).

866761067521381 is an equidigital number, since it uses as much as digits as its factorization.

866761067521381 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 121927680, while the sum is 67.

The spelling of 866761067521381 in words is "eight hundred sixty-six trillion, seven hundred sixty-one billion, sixty-seven million, five hundred twenty-one thousand, three hundred eighty-one".