266721666 has 8 divisors (see below), whose sum is σ = 533443344. Its totient is φ = 88907220.

The previous prime is 266721661. The next prime is 266721691. The reversal of 266721666 is 666127662.

It is a sphenic number, since it is the product of 3 distinct primes.

266721666 is an admirable number.

It is a super-2 number, since 2×266721666² = 142280894227631112, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (266721661) 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, 22226800 + ... + 22226811.

It is an arithmetic number, because the mean of its divisors is an integer number (66680418).

Almost surely, 2^266721666 is an apocalyptic number.

266721666 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

266721666 is a wasteful number, since it uses less digits than its factorization.

266721666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 44453616.

The product of its digits is 217728, while the sum is 42.

The square root of 266721666 is about 16331.6155355188. The cubic root of 266721666 is about 643.7038377556.

The spelling of 266721666 in words is "two hundred sixty-six million, seven hundred twenty-one thousand, six hundred sixty-six".