66440765 has 4 divisors (see below), whose sum is σ = 79728924. Its totient is φ = 53152608.

The previous prime is 66440761. The next prime is 66440771. The reversal of 66440765 is 56704466.

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 33790969 + 32649796 = 5813^2 + 5714^2 .

It is a cyclic number.

It is not a de Polignac number, because 66440765 - 2² = 66440761 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66440761) 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, 6644072 + ... + 6644081.

It is an arithmetic number, because the mean of its divisors is an integer number (19932231).

Almost surely, 2^66440765 is an apocalyptic number.

It is an amenable number.

66440765 is a deficient number, since it is larger than the sum of its proper divisors (13288159).

66440765 is a wasteful number, since it uses less digits than its factorization.

66440765 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13288158.

The product of its (nonzero) digits is 120960, while the sum is 38.

The square root of 66440765 is about 8151.1204751249. The cubic root of 66440765 is about 405.0216215658.

The spelling of 66440765 in words is "sixty-six million, four hundred forty thousand, seven hundred sixty-five".