66116561 has 8 divisors (see below), whose sum is σ = 79538880. Its totient is φ = 53688528.

The previous prime is 66116551. The next prime is 66116563. The reversal of 66116561 is 16561166.

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

It is not a de Polignac number, because 66116561 - 2²² = 61922257 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66116563) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 248426 + ... + 248691.

It is an arithmetic number, because the mean of its divisors is an integer number (9942360).

Almost surely, 2^66116561 is an apocalyptic number.

It is an amenable number.

66116561 is a deficient number, since it is larger than the sum of its proper divisors (13422319).

66116561 is a wasteful number, since it uses less digits than its factorization.

66116561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 497143.

The product of its digits is 6480, while the sum is 32.

The square root of 66116561 is about 8131.2090736864. The cubic root of 66116561 is about 404.3617666814.

The spelling of 66116561 in words is "sixty-six million, one hundred sixteen thousand, five hundred sixty-one".