66750817 has 4 divisors (see below), whose sum is σ = 76286656. Its totient is φ = 57214980.

The previous prime is 66750811. The next prime is 66750821. The reversal of 66750817 is 71805766.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 71805766 = 2 ⋅35902883.

It is a cyclic number.

It is not a de Polignac number, because 66750817 - 2¹⁹ = 66226529 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 66750817.

It is not an unprimeable number, because it can be changed into a prime (66750811) 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, 4767909 + ... + 4767922.

It is an arithmetic number, because the mean of its divisors is an integer number (19071664).

Almost surely, 2^66750817 is an apocalyptic number.

It is an amenable number.

66750817 is a deficient number, since it is larger than the sum of its proper divisors (9535839).

66750817 is an equidigital number, since it uses as much as digits as its factorization.

66750817 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9535838.

The product of its (nonzero) digits is 70560, while the sum is 40.

The square root of 66750817 is about 8170.1173186191. The cubic root of 66750817 is about 405.6506677474.

The spelling of 66750817 in words is "sixty-six million, seven hundred fifty thousand, eight hundred seventeen".