665767566 has 96 divisors (see below), whose sum is σ = 1615507680. Its totient is φ = 203046912.

The previous prime is 665767559. The next prime is 665767567.

665767566 is a `hidden beast` number, since 6 + 6 + 5 + 76 + 7 + 566 = 666.

665767566 is nontrivially palindromic in base 10.

It is a super-3 number, since 3×665767566³ (a number of 27 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (665767567) 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, 576846 + ... + 577998.

It is an arithmetic number, because the mean of its divisors is an integer number (16828205).

Almost surely, 2^665767566 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 665767566, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (807753840).

665767566 is an abundant number, since it is smaller than the sum of its proper divisors (949740114).

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

665767566 is a wasteful number, since it uses less digits than its factorization.

665767566 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1235 (or 1212 counting only the distinct ones).

The product of its digits is 9525600, while the sum is 54.

The square root of 665767566 is about 25802.4720908676. The cubic root of 665767566 is about 873.1875696681.

The spelling of 665767566 in words is "six hundred sixty-five million, seven hundred sixty-seven thousand, five hundred sixty-six".