66071581 has 4 divisors (see below), whose sum is σ = 67057792. Its totient is φ = 65085372.

The previous prime is 66071573. The next prime is 66071587. The reversal of 66071581 is 18517066.

66071581 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 66071581 - 2³ = 66071573 is a prime.

It is a super-2 number, since 2×66071581² = 8730907631679122, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66071587) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 493005 + ... + 493138.

It is an arithmetic number, because the mean of its divisors is an integer number (16764448).

Almost surely, 2^66071581 is an apocalyptic number.

It is an amenable number.

66071581 is a deficient number, since it is larger than the sum of its proper divisors (986211).

66071581 is an equidigital number, since it uses as much as digits as its factorization.

66071581 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 986210.

The product of its (nonzero) digits is 10080, while the sum is 34.

The square root of 66071581 is about 8128.4427167816. The cubic root of 66071581 is about 404.2700482672.

The spelling of 66071581 in words is "sixty-six million, seventy-one thousand, five hundred eighty-one".