866761256758761 has 160 divisors (see below), whose sum is σ = 1698696407654400. Its totient is φ = 427647311095680.

The previous prime is 866761256758721. The next prime is 866761256758777. The reversal of 866761256758761 is 167857652167668.

866761256758761 is a `hidden beast` number, since 8 + 6 + 6 + 7 + 6 + 1 + 25 + 6 + 7 + 587 + 6 + 1 = 666.

It is not a de Polignac number, because 866761256758761 - 2²⁶ = 866761189649897 is a prime.

It is a super-2 number, since 2×866761256758761² (a number of 31 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (81).

It is not an unprimeable number, because it can be changed into a prime (866761256758721) by changing a digit.

It is a polite number, since it can be written in 159 ways as a sum of consecutive naturals, for example, 28106925 + ... + 50234666.

It is an arithmetic number, because the mean of its divisors is an integer number (10616852547840).

Almost surely, 2^{866761256758761} is an apocalyptic number.

866761256758761 is a gapful number since it is divisible by the number (81) formed by its first and last digit.

It is an amenable number.

866761256758761 is a deficient number, since it is larger than the sum of its proper divisors (831935150895639).

866761256758761 is a wasteful number, since it uses less digits than its factorization.

866761256758761 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 78341721 (or 78341712 counting only the distinct ones).

The product of its digits is 8534937600, while the sum is 81.

The spelling of 866761256758761 in words is "eight hundred sixty-six trillion, seven hundred sixty-one billion, two hundred fifty-six million, seven hundred fifty-eight thousand, seven hundred sixty-one".