66138845 has 6 divisors (see below), whose sum is σ = 79388442. Its totient is φ = 52896528.

The previous prime is 66138833. The next prime is 66138851. The reversal of 66138845 is 54883166.

It can be written as a sum of positive squares in 3 ways, for example, as 5750404 + 60388441 = 2398^2 + 7771^2 .

It is not a de Polignac number, because 66138845 - 2²⁰ = 65090269 is a prime.

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 5 ways as a sum of consecutive naturals, for example, 16367 + ... + 20003.

It is an arithmetic number, because the mean of its divisors is an integer number (13231407).

Almost surely, 2^66138845 is an apocalyptic number.

It is an amenable number.

66138845 is a deficient number, since it is larger than the sum of its proper divisors (13249597).

66138845 is an frugal number, since it uses more digits than its factorization.

66138845 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7279 (or 3642 counting only the distinct ones).

The product of its digits is 138240, while the sum is 41.

The square root of 66138845 is about 8132.5792341667. The cubic root of 66138845 is about 404.4071904266.

The spelling of 66138845 in words is "sixty-six million, one hundred thirty-eight thousand, eight hundred forty-five".