67166216561 has 4 divisors (see below), whose sum is σ = 67760607972. Its totient is φ = 66571825152.

The previous prime is 67166216503. The next prime is 67166216563. The reversal of 67166216561 is 16561266176.

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 10892888161 + 56273328400 = 104369^2 + 237220^2 .

It is a cyclic number.

It is not a de Polignac number, because 67166216561 - 2³⁴ = 49986347377 is a prime.

It is a super-2 number, since 2×67166216561² (a number of 22 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (67166216563) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 297195536 + ... + 297195761.

It is an arithmetic number, because the mean of its divisors is an integer number (16940151993).

Almost surely, 2^67166216561 is an apocalyptic number.

It is an amenable number.

67166216561 is a deficient number, since it is larger than the sum of its proper divisors (594391411).

67166216561 is a wasteful number, since it uses less digits than its factorization.

67166216561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 594391410.

The product of its digits is 544320, while the sum is 47.

The spelling of 67166216561 in words is "sixty-seven billion, one hundred sixty-six million, two hundred sixteen thousand, five hundred sixty-one".