66153764581 has 4 divisors (see below), whose sum is σ = 66835762252. Its totient is φ = 65471766912.

The previous prime is 66153764557. The next prime is 66153764587. The reversal of 66153764581 is 18546735166.

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 24596903556 + 41556861025 = 156834^2 + 203855^2 .

It is a cyclic number.

It is not a de Polignac number, because 66153764581 - 2⁵ = 66153764549 is a prime.

It is a super-2 number, since 2×66153764581² (a number of 22 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66153764587) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 340998690 + ... + 340998883.

It is an arithmetic number, because the mean of its divisors is an integer number (16708940563).

Almost surely, 2^66153764581 is an apocalyptic number.

It is an amenable number.

66153764581 is a deficient number, since it is larger than the sum of its proper divisors (681997671).

66153764581 is an equidigital number, since it uses as much as digits as its factorization.

66153764581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 681997670.

The product of its digits is 3628800, while the sum is 52.

The spelling of 66153764581 in words is "sixty-six billion, one hundred fifty-three million, seven hundred sixty-four thousand, five hundred eighty-one".