66129817 has 4 divisors (see below), whose sum is σ = 71216740. Its totient is φ = 61042896.

The previous prime is 66129803. The next prime is 66129821. The reversal of 66129817 is 71892166.

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 31036041 + 35093776 = 5571^2 + 5924^2 .

It is a cyclic number.

It is not a de Polignac number, because 66129817 - 2¹⁵ = 66097049 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 66129817.

It is not an unprimeable number, because it can be changed into a prime (66129857) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2543442 + ... + 2543467.

It is an arithmetic number, because the mean of its divisors is an integer number (17804185).

Almost surely, 2^66129817 is an apocalyptic number.

It is an amenable number.

66129817 is a deficient number, since it is larger than the sum of its proper divisors (5086923).

66129817 is a wasteful number, since it uses less digits than its factorization.

66129817 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5086922.

The product of its digits is 36288, while the sum is 40.

The square root of 66129817 is about 8132.0241637614. The cubic root of 66129817 is about 404.3887889650.

The spelling of 66129817 in words is "sixty-six million, one hundred twenty-nine thousand, eight hundred seventeen".