66753781 has 8 divisors (see below), whose sum is σ = 72405144. Its totient is φ = 61294080.

The previous prime is 66753779. The next prime is 66753787. The reversal of 66753781 is 18735766.

It can be written as a sum of positive squares in 4 ways, for example, as 2353156 + 64400625 = 1534^2 + 8025^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 66753781 - 2¹ = 66753779 is a prime.

It is a super-2 number, since 2×66753781² = 8912134555591922, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66753787) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 47190 + ... + 48583.

It is an arithmetic number, because the mean of its divisors is an integer number (9050643).

Almost surely, 2^66753781 is an apocalyptic number.

It is an amenable number.

66753781 is a deficient number, since it is larger than the sum of its proper divisors (5651363).

66753781 is a wasteful number, since it uses less digits than its factorization.

66753781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 95831.

The product of its digits is 211680, while the sum is 43.

The square root of 66753781 is about 8170.2987093496. The cubic root of 66753781 is about 405.6566718226.

The spelling of 66753781 in words is "sixty-six million, seven hundred fifty-three thousand, seven hundred eighty-one".