66620161565 has 8 divisors (see below), whose sum is σ = 80084696760. Its totient is φ = 53202460672.

The previous prime is 66620161513. The next prime is 66620161577. The reversal of 66620161565 is 56516102666.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 6287538436 + 60332623129 = 79294^2 + 245627^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 66620161565 - 2⁶ = 66620161501 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 11705444 + ... + 11711133.

It is an arithmetic number, because the mean of its divisors is an integer number (10010587095).

Almost surely, 2^66620161565 is an apocalyptic number.

It is an amenable number.

66620161565 is a deficient number, since it is larger than the sum of its proper divisors (13464535195).

66620161565 is a wasteful number, since it uses less digits than its factorization.

66620161565 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23417151.

The product of its (nonzero) digits is 388800, while the sum is 44.

The spelling of 66620161565 in words is "sixty-six billion, six hundred twenty million, one hundred sixty-one thousand, five hundred sixty-five".