66461355601 has 9 divisors (see below), whose sum is σ = 67429185609. Its totient is φ = 65507234100.

The previous prime is 66461355599. The next prime is 66461355637. The reversal of 66461355601 is 10655316466.

The square root of 66461355601 is 257801.

It is a perfect power (a square), and thus also a powerful number.

It is not a de Polignac number, because 66461355601 - 2¹ = 66461355599 is a prime.

It is a super-2 number, since 2×66461355601² (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 (66461355671) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 18302056 + ... + 18305686.

Almost surely, 2^66461355601 is an apocalyptic number.

66461355601 is the 257801-st square number.

66461355601 is the 128901-st centered octagonal number.

It is an amenable number.

66461355601 is a deficient number, since it is larger than the sum of its proper divisors (967830008).

66461355601 is an frugal number, since it uses more digits than its factorization.

66461355601 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7404 (or 3702 counting only the distinct ones).

The product of its (nonzero) digits is 388800, while the sum is 43.

The spelling of 66461355601 in words is "sixty-six billion, four hundred sixty-one million, three hundred fifty-five thousand, six hundred one".