66211278 has 64 divisors (see below), whose sum is σ = 157068288. Its totient is φ = 18213120.

The previous prime is 66211267. The next prime is 66211307. The reversal of 66211278 is 87211266.

66211278 is a nontrivial binomial coefficient, being equal to C(11508, 2).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 212743 + ... + 213053.

It is an arithmetic number, because the mean of its divisors is an integer number (2454192).

Almost surely, 2^66211278 is an apocalyptic number.

66211278 is the 11507-th triangular number and also the 5754-th hexagonal number.

It is a practical number, because each smaller number is the sum of distinct divisors of 66211278, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (78534144).

66211278 is an abundant number, since it is smaller than the sum of its proper divisors (90857010).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

66211278 is a wasteful number, since it uses less digits than its factorization.

66211278 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 497.

The product of its digits is 8064, while the sum is 33.

The square root of 66211278 is about 8137.0312768233. The cubic root of 66211278 is about 404.5547675384.

The spelling of 66211278 in words is "sixty-six million, two hundred eleven thousand, two hundred seventy-eight".