66565405 has 16 divisors (see below), whose sum is σ = 82432944. Its totient is φ = 51563520.

The previous prime is 66565391. The next prime is 66565439. The reversal of 66565405 is 50456566.

It can be written as a sum of positive squares in 8 ways, for example, as 15256836 + 51308569 = 3906^2 + 7163^2 .

It is not a de Polignac number, because 66565405 - 2⁹ = 66564893 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (37).

It is a Duffinian number.

It is a congruent number.

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, 43839 + ... + 45331.

It is an arithmetic number, because the mean of its divisors is an integer number (5152059).

Almost surely, 2^66565405 is an apocalyptic number.

It is an amenable number.

66565405 is a deficient number, since it is larger than the sum of its proper divisors (15867539).

66565405 is a wasteful number, since it uses less digits than its factorization.

66565405 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1776.

The product of its (nonzero) digits is 108000, while the sum is 37.

The square root of 66565405 is about 8158.7624674334. The cubic root of 66565405 is about 405.2747310360.

The spelling of 66565405 in words is "sixty-six million, five hundred sixty-five thousand, four hundred five".