66780869 has 4 divisors (see below), whose sum is σ = 66799596. Its totient is φ = 66762144.

The previous prime is 66780827. The next prime is 66780871. The reversal of 66780869 is 96808766.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 63760225 + 3020644 = 7985^2 + 1738^2 .

It is a cyclic number.

It is not a de Polignac number, because 66780869 - 2⁸ = 66780613 is a prime.

It is a super-2 number, since 2×66780869² = 8919368928790322, 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 (66780899) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2174 + ... + 11759.

It is an arithmetic number, because the mean of its divisors is an integer number (16699899).

Almost surely, 2^66780869 is an apocalyptic number.

It is an amenable number.

66780869 is a deficient number, since it is larger than the sum of its proper divisors (18727).

66780869 is a wasteful number, since it uses less digits than its factorization.

66780869 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18726.

The product of its (nonzero) digits is 870912, while the sum is 50.

The square root of 66780869 is about 8171.9562529421. The cubic root of 66780869 is about 405.7115348419.

The spelling of 66780869 in words is "sixty-six million, seven hundred eighty thousand, eight hundred sixty-nine".