66105781 has 16 divisors (see below), whose sum is σ = 76656384. Its totient is φ = 55839744.

The previous prime is 66105779. The next prime is 66105827. The reversal of 66105781 is 18750166.

It is a cyclic number.

It is not a de Polignac number, because 66105781 - 2¹ = 66105779 is a prime.

It is a super-2 number, since 2×66105781² = 8739948563239922, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66105701) 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, 225471 + ... + 225763.

It is an arithmetic number, because the mean of its divisors is an integer number (4791024).

Almost surely, 2^66105781 is an apocalyptic number.

It is an amenable number.

66105781 is a deficient number, since it is larger than the sum of its proper divisors (10550603).

66105781 is a wasteful number, since it uses less digits than its factorization.

66105781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 660.

The product of its (nonzero) digits is 10080, while the sum is 34.

The square root of 66105781 is about 8130.5461686162. The cubic root of 66105781 is about 404.3397890472.

The spelling of 66105781 in words is "sixty-six million, one hundred five thousand, seven hundred eighty-one".