66693881 has 4 divisors (see below), whose sum is σ = 68993700. Its totient is φ = 64394064.

The previous prime is 66693871. The next prime is 66693883. The reversal of 66693881 is 18839666.

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 29593600 + 37100281 = 5440^2 + 6091^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66693881 is a prime.

It is a super-2 number, since 2×66693881² = 8896147525684322, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66693883) 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, 1149866 + ... + 1149923.

It is an arithmetic number, because the mean of its divisors is an integer number (17248425).

Almost surely, 2^66693881 is an apocalyptic number.

It is an amenable number.

66693881 is a deficient number, since it is larger than the sum of its proper divisors (2299819).

66693881 is a wasteful number, since it uses less digits than its factorization.

66693881 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2299818.

The product of its digits is 373248, while the sum is 47.

The square root of 66693881 is about 8166.6321699952. The cubic root of 66693881 is about 405.5352998898.

The spelling of 66693881 in words is "sixty-six million, six hundred ninety-three thousand, eight hundred eighty-one".