66440389 has 4 divisors (see below), whose sum is σ = 66680524. Its totient is φ = 66200256.

The previous prime is 66440383. The next prime is 66440393. The reversal of 66440389 is 98304466.

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 9180900 + 57259489 = 3030^2 + 7567^2 .

It is a cyclic number.

It is not a de Polignac number, because 66440389 - 2⁵ = 66440357 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 (66440383) 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, 119652 + ... + 120205.

It is an arithmetic number, because the mean of its divisors is an integer number (16670131).

Almost surely, 2^66440389 is an apocalyptic number.

It is an amenable number.

66440389 is a deficient number, since it is larger than the sum of its proper divisors (240135).

66440389 is a wasteful number, since it uses less digits than its factorization.

66440389 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 240134.

The product of its (nonzero) digits is 124416, while the sum is 40.

The square root of 66440389 is about 8151.0974107785. The cubic root of 66440389 is about 405.0208575348.

The spelling of 66440389 in words is "sixty-six million, four hundred forty thousand, three hundred eighty-nine".