66766661 has 6 divisors (see below), whose sum is σ = 72297810. Its totient is φ = 61630608.

The previous prime is 66766657. The next prime is 66766663. The reversal of 66766661 is 16666766.

It can be written as a sum of positive squares in 3 ways, for example, as 1464100 + 65302561 = 1210^2 + 8081^2 .

It is not a de Polignac number, because 66766661 - 2² = 66766657 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66766663) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 197366 + ... + 197703.

It is an arithmetic number, because the mean of its divisors is an integer number (12049635).

Almost surely, 2^66766661 is an apocalyptic number.

It is an amenable number.

66766661 is a deficient number, since it is larger than the sum of its proper divisors (5531149).

66766661 is a wasteful number, since it uses less digits than its factorization.

66766661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 395095 (or 395082 counting only the distinct ones).

The product of its digits is 326592, while the sum is 44.

The square root of 66766661 is about 8171.0868922072. The cubic root of 66766661 is about 405.6827603420.

The spelling of 66766661 in words is "sixty-six million, seven hundred sixty-six thousand, six hundred sixty-one".