666777722688 has 336 divisors, whose sum is σ = 2508205539840. Its totient is φ = 164073600000.

The previous prime is 666777722683. The next prime is 666777722717. The reversal of 666777722688 is 886227777666.

666777722688 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a tau number, because it is divible by the number of its divisors (336).

It is a super-3 number, since 3×666777722688³ (a number of 36 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (72).

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666777722683) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 447063 + ... + 1238313.

It is an arithmetic number, because the mean of its divisors is an integer number (7464897440).

Almost surely, 2^666777722688 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 666777722688, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1254102769920).

666777722688 is an abundant number, since it is smaller than the sum of its proper divisors (1841427817152).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

666777722688 is a wasteful number, since it uses less digits than its factorization.

666777722688 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 791306 (or 791293 counting only the distinct ones).

The product of its digits is 796594176, while the sum is 72.

The spelling of 666777722688 in words is "six hundred sixty-six billion, seven hundred seventy-seven million, seven hundred twenty-two thousand, six hundred eighty-eight".