66751272641 has 4 divisors (see below), whose sum is σ = 66949347972. Its totient is φ = 66553197312.

The previous prime is 66751272631. The next prime is 66751272647. The reversal of 66751272641 is 14627215766.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 14627215766 = 2 ⋅7313607883.

It can be written as a sum of positive squares in 2 ways, for example, as 9369465616 + 57381807025 = 96796^2 + 239545^2 .

It is a cyclic number.

It is not a de Polignac number, because 66751272641 - 2¹⁸ = 66751010497 is a prime.

It is a super-2 number, since 2×66751272641² (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 (66751272647) 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, 99037160 + ... + 99037833.

It is an arithmetic number, because the mean of its divisors is an integer number (16737336993).

Almost surely, 2^66751272641 is an apocalyptic number.

It is an amenable number.

66751272641 is a deficient number, since it is larger than the sum of its proper divisors (198075331).

66751272641 is a wasteful number, since it uses less digits than its factorization.

66751272641 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 198075330.

The product of its digits is 846720, while the sum is 47.

The spelling of 66751272641 in words is "sixty-six billion, seven hundred fifty-one million, two hundred seventy-two thousand, six hundred forty-one".