66797781 has 8 divisors (see below), whose sum is σ = 89329344. Its totient is φ = 44399040.

The previous prime is 66797779. The next prime is 66797821. The reversal of 66797781 is 18779766.

It is a happy number.

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

It is not a de Polignac number, because 66797781 - 2¹ = 66797779 is a prime.

It is a super-2 number, since 2×66797781² = 8923887093047922, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66797741) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 32025 + ... + 34046.

It is an arithmetic number, because the mean of its divisors is an integer number (11166168).

Almost surely, 2^66797781 is an apocalyptic number.

It is an amenable number.

66797781 is a deficient number, since it is larger than the sum of its proper divisors (22531563).

66797781 is a wasteful number, since it uses less digits than its factorization.

66797781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 66411.

The product of its digits is 889056, while the sum is 51.

The square root of 66797781 is about 8172.9909457921. The cubic root of 66797781 is about 405.7457802501.

The spelling of 66797781 in words is "sixty-six million, seven hundred ninety-seven thousand, seven hundred eighty-one".