66256774464561 has 16 divisors (see below), whose sum is σ = 88381339851264. Its totient is φ = 44151699993984.

The previous prime is 66256774464533. The next prime is 66256774464577. The reversal of 66256774464561 is 16546447765266.

It is not a de Polignac number, because 66256774464561 - 2²³ = 66256766075953 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (66256774464521) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 66992925 + ... + 67974741.

It is an arithmetic number, because the mean of its divisors is an integer number (5523833740704).

Almost surely, 2^{66256774464561} is an apocalyptic number.

It is an amenable number.

66256774464561 is a deficient number, since it is larger than the sum of its proper divisors (22124565386703).

66256774464561 is a wasteful number, since it uses less digits than its factorization.

66256774464561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 991720.

The product of its digits is 1219276800, while the sum is 69.

The spelling of 66256774464561 in words is "sixty-six trillion, two hundred fifty-six billion, seven hundred seventy-four million, four hundred sixty-four thousand, five hundred sixty-one".