666761568 has 96 divisors (see below), whose sum is σ = 1936472832. Its totient is φ = 199180800.

The previous prime is 666761561. The next prime is 666761593. The reversal of 666761568 is 865167666.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (96).

It is a Smith number, since the sum of its digits (51) coincides with the sum of the digits of its prime factors.

It is a self number, because there is not a number n which added to its sum of digits gives 666761568.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666761561) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 70530 + ... + 79422.

It is an arithmetic number, because the mean of its divisors is an integer number (20171592).

Almost surely, 2^666761568 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 666761568, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (968236416).

666761568 is an abundant number, since it is smaller than the sum of its proper divisors (1269711264).

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

666761568 is a wasteful number, since it uses less digits than its factorization.

666761568 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8988 (or 8980 counting only the distinct ones).

The product of its digits is 2177280, while the sum is 51.

The square root of 666761568 is about 25821.7266657364. The cubic root of 666761568 is about 873.6219147450.

The spelling of 666761568 in words is "six hundred sixty-six million, seven hundred sixty-one thousand, five hundred sixty-eight".