66291689 has 4 divisors (see below), whose sum is σ = 67378500. Its totient is φ = 65204880.

The previous prime is 66291683. The next prime is 66291691. The reversal of 66291689 is 98619266.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 98619266 = 2 ⋅49309633.

It can be written as a sum of positive squares in 2 ways, for example, as 13249600 + 53042089 = 3640^2 + 7283^2 .

It is a cyclic number.

It is not a de Polignac number, because 66291689 - 2¹² = 66287593 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66291683) 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, 543314 + ... + 543435.

It is an arithmetic number, because the mean of its divisors is an integer number (16844625).

Almost surely, 2^66291689 is an apocalyptic number.

It is an amenable number.

66291689 is a deficient number, since it is larger than the sum of its proper divisors (1086811).

66291689 is a wasteful number, since it uses less digits than its factorization.

66291689 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1086810.

The product of its digits is 279936, while the sum is 47.

The square root of 66291689 is about 8141.9708302106. The cubic root of 66291689 is about 404.7184732504.

The spelling of 66291689 in words is "sixty-six million, two hundred ninety-one thousand, six hundred eighty-nine".