66278261 has 12 divisors (see below), whose sum is σ = 76553568. Its totient is φ = 56210952.

The previous prime is 66278243. The next prime is 66278273. The reversal of 66278261 is 16287266.

It is a happy number.

It is a de Polignac number, because none of the positive numbers 2^k-66278261 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66278231) 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 11 ways as a sum of consecutive naturals, for example, 79730 + ... + 80556.

It is an arithmetic number, because the mean of its divisors is an integer number (6379464).

Almost surely, 2^66278261 is an apocalyptic number.

It is an amenable number.

66278261 is a deficient number, since it is larger than the sum of its proper divisors (10275307).

66278261 is an equidigital number, since it uses as much as digits as its factorization.

66278261 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1048 (or 941 counting only the distinct ones).

The product of its digits is 48384, while the sum is 38.

The square root of 66278261 is about 8141.1461723765. The cubic root of 66278261 is about 404.6911449044.

The spelling of 66278261 in words is "sixty-six million, two hundred seventy-eight thousand, two hundred sixty-one".