66581222401 has 4 divisors (see below), whose sum is σ = 66582188100. Its totient is φ = 66580256704.

The previous prime is 66581222333. The next prime is 66581222413. The reversal of 66581222401 is 10422218566.

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 43172528400 + 23408694001 = 207780^2 + 152999^2 .

It is a cyclic number.

It is not a de Polignac number, because 66581222401 - 2¹¹ = 66581220353 is a prime.

It is a super-2 number, since 2×66581222401² (a number of 22 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66581222471) 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, 370756 + ... + 520213.

It is an arithmetic number, because the mean of its divisors is an integer number (16645547025).

Almost surely, 2^66581222401 is an apocalyptic number.

It is an amenable number.

66581222401 is a deficient number, since it is larger than the sum of its proper divisors (965699).

66581222401 is an equidigital number, since it uses as much as digits as its factorization.

66581222401 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 965698.

The product of its (nonzero) digits is 46080, while the sum is 37.

The spelling of 66581222401 in words is "sixty-six billion, five hundred eighty-one million, two hundred twenty-two thousand, four hundred one".