66215565 has 24 divisors (see below), whose sum is σ = 123603480. Its totient is φ = 32598144.

The previous prime is 66215563. The next prime is 66215587. The reversal of 66215565 is 56551266.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 459684 + 65755881 = 678^2 + 8109^2 .

It is not a de Polignac number, because 66215565 - 2¹ = 66215563 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66215563) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 56010 + ... + 57179.

It is an arithmetic number, because the mean of its divisors is an integer number (5150145).

Almost surely, 2^66215565 is an apocalyptic number.

66215565 is a gapful number since it is divisible by the number (65) formed by its first and last digit.

It is an amenable number.

66215565 is a deficient number, since it is larger than the sum of its proper divisors (57387915).

66215565 is a wasteful number, since it uses less digits than its factorization.

66215565 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 113213 (or 113210 counting only the distinct ones).

The product of its digits is 54000, while the sum is 36.

The square root of 66215565 is about 8137.2946978710. The cubic root of 66215565 is about 404.5634986232.

The spelling of 66215565 in words is "sixty-six million, two hundred fifteen thousand, five hundred sixty-five".