66722081 has 4 divisors (see below), whose sum is σ = 66740100. Its totient is φ = 66704064.

The previous prime is 66722077. The next prime is 66722087. The reversal of 66722081 is 18022766.

66722081 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.

It can be written as a sum of positive squares in 2 ways, for example, as 48094225 + 18627856 = 6935^2 + 4316^2 .

It is a cyclic number.

It is not a de Polignac number, because 66722081 - 2² = 66722077 is a prime.

It is a super-2 number, since 2×66722081² = 8903672185941122, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66722087) 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, 1196 + ... + 11613.

It is an arithmetic number, because the mean of its divisors is an integer number (16685025).

Almost surely, 2^66722081 is an apocalyptic number.

It is an amenable number.

66722081 is a deficient number, since it is larger than the sum of its proper divisors (18019).

66722081 is a wasteful number, since it uses less digits than its factorization.

66722081 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18018.

The product of its (nonzero) digits is 8064, while the sum is 32.

The square root of 66722081 is about 8168.3585254321. The cubic root of 66722081 is about 405.5924489807.

The spelling of 66722081 in words is "sixty-six million, seven hundred twenty-two thousand, eighty-one".