66347881 has 4 divisors (see below), whose sum is σ = 67966164. Its totient is φ = 64729600.

The previous prime is 66347873. The next prime is 66347899. The reversal of 66347881 is 18874366.

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 883600 + 65464281 = 940^2 + 8091^2 .

It is a cyclic number.

It is not a de Polignac number, because 66347881 - 2³ = 66347873 is a prime.

It is a super-2 number, since 2×66347881² = 8804082626380322, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66347851) 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, 809080 + ... + 809161.

It is an arithmetic number, because the mean of its divisors is an integer number (16991541).

Almost surely, 2^66347881 is an apocalyptic number.

It is an amenable number.

66347881 is a deficient number, since it is larger than the sum of its proper divisors (1618283).

66347881 is a wasteful number, since it uses less digits than its factorization.

66347881 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1618282.

The product of its digits is 193536, while the sum is 43.

The square root of 66347881 is about 8145.4208608273. The cubic root of 66347881 is about 404.8327938543.

The spelling of 66347881 in words is "sixty-six million, three hundred forty-seven thousand, eight hundred eighty-one".