66681340073 has 4 divisors (see below), whose sum is σ = 70603771860. Its totient is φ = 62758908288.

The previous prime is 66681340021. The next prime is 66681340079. The reversal of 66681340073 is 37004318666.

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 59217762409 + 7463577664 = 243347^2 + 86392^2 .

It is a cyclic number.

It is not a de Polignac number, because 66681340073 - 2¹⁶ = 66681274537 is a prime.

It is a super-2 number, since 2×66681340073² (a number of 22 digits) contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (66681340079) 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, 1961215868 + ... + 1961215901.

It is an arithmetic number, because the mean of its divisors is an integer number (17650942965).

Almost surely, 2^66681340073 is an apocalyptic number.

It is an amenable number.

66681340073 is a deficient number, since it is larger than the sum of its proper divisors (3922431787).

66681340073 is a wasteful number, since it uses less digits than its factorization.

66681340073 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3922431786.

The product of its (nonzero) digits is 435456, while the sum is 44.

The spelling of 66681340073 in words is "sixty-six billion, six hundred eighty-one million, three hundred forty thousand, seventy-three".