66897865 has 4 divisors (see below), whose sum is σ = 80277444. Its totient is φ = 53518288.

The previous prime is 66897863. The next prime is 66897881. The reversal of 66897865 is 56879866.

It is a happy number.

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 26790976 + 40106889 = 5176^2 + 6333^2 .

It is a cyclic number.

It is not a de Polignac number, because 66897865 - 2¹ = 66897863 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66897863) 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, 6689782 + ... + 6689791.

It is an arithmetic number, because the mean of its divisors is an integer number (20069361).

Almost surely, 2^66897865 is an apocalyptic number.

It is an amenable number.

66897865 is a deficient number, since it is larger than the sum of its proper divisors (13379579).

66897865 is a wasteful number, since it uses less digits than its factorization.

66897865 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13379578.

The product of its digits is 4354560, while the sum is 55.

The square root of 66897865 is about 8179.1115043139. Note that the first 3 decimals coincide. The cubic root of 66897865 is about 405.9483238847.

The spelling of 66897865 in words is "sixty-six million, eight hundred ninety-seven thousand, eight hundred sixty-five".