66211261 has 4 divisors (see below), whose sum is σ = 66437532. Its totient is φ = 65984992.

The previous prime is 66211259. The next prime is 66211267. The reversal of 66211261 is 16211266.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 16211266 = 2 ⋅8105633.

It can be written as a sum of positive squares in 2 ways, for example, as 57836025 + 8375236 = 7605^2 + 2894^2 .

It is a cyclic number.

It is not a de Polignac number, because 66211261 - 2¹ = 66211259 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66211267) 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 3 ways as a sum of consecutive naturals, for example, 112696 + ... + 113281.

It is an arithmetic number, because the mean of its divisors is an integer number (16609383).

Almost surely, 2^66211261 is an apocalyptic number.

It is an amenable number.

66211261 is a deficient number, since it is larger than the sum of its proper divisors (226271).

66211261 is a wasteful number, since it uses less digits than its factorization.

66211261 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 226270.

The product of its digits is 864, while the sum is 25.

The square root of 66211261 is about 8137.0302322162. The cubic root of 66211261 is about 404.5547329147.

The spelling of 66211261 in words is "sixty-six million, two hundred eleven thousand, two hundred sixty-one".