866121340118081 has 4 divisors (see below), whose sum is σ = 917069654242692. Its totient is φ = 815173025993472.

The previous prime is 866121340118063. The next prime is 866121340118087. The reversal of 866121340118081 is 180811043121668.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 753519848499856 + 112601491618225 = 27450316^2 + 10611385^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-866121340118081 is a prime.

It is a super-2 number, since 2×866121340118081² (a number of 31 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (866121340118087) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 25474157062280 + ... + 25474157062313.

It is an arithmetic number, because the mean of its divisors is an integer number (229267413560673).

Almost surely, 2^{866121340118081} is an apocalyptic number.

It is an amenable number.

866121340118081 is a deficient number, since it is larger than the sum of its proper divisors (50948314124611).

866121340118081 is a wasteful number, since it uses less digits than its factorization.

866121340118081 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 50948314124610.

The product of its (nonzero) digits is 442368, while the sum is 50.

The spelling of 866121340118081 in words is "eight hundred sixty-six trillion, one hundred twenty-one billion, three hundred forty million, one hundred eighteen thousand, eighty-one".