66801865 has 16 divisors (see below), whose sum is σ = 87796800. Its totient is φ = 48491712.

The previous prime is 66801859. The next prime is 66801883. The reversal of 66801865 is 56810866.

It is a happy number.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66801865 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4875 + ... + 12544.

It is an arithmetic number, because the mean of its divisors is an integer number (5487300).

Almost surely, 2^66801865 is an apocalyptic number.

66801865 is a gapful number since it is divisible by the number (65) formed by its first and last digit.

It is an amenable number.

66801865 is a deficient number, since it is larger than the sum of its proper divisors (20994935).

66801865 is a wasteful number, since it uses less digits than its factorization.

66801865 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17496.

The product of its (nonzero) digits is 69120, while the sum is 40.

The square root of 66801865 is about 8173.2407893075. The cubic root of 66801865 is about 405.7540491475.

Subtracting from 66801865 its reverse (56810866), we obtain a palindrome (9990999).

The spelling of 66801865 in words is "sixty-six million, eight hundred one thousand, eight hundred sixty-five".