66621641 has 2 divisors, whose sum is σ = 66621642. Its totient is φ = 66621640.

The previous prime is 66621617. The next prime is 66621647. The reversal of 66621641 is 14612666.

66621641 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 65934400 + 687241 = 8120^2 + 829^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66621641 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 66621598 and 66621607.

It is not a weakly prime, because it can be changed into another prime (66621647) 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 as a sum of consecutive naturals, namely, 33310820 + 33310821.

It is an arithmetic number, because the mean of its divisors is an integer number (33310821).

Almost surely, 2^66621641 is an apocalyptic number.

It is an amenable number.

66621641 is a deficient number, since it is larger than the sum of its proper divisors (1).

66621641 is an equidigital number, since it uses as much as digits as its factorization.

66621641 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 10368, while the sum is 32.

The square root of 66621641 is about 8162.2080958525. The cubic root of 66621641 is about 405.3888274131.

The spelling of 66621641 in words is "sixty-six million, six hundred twenty-one thousand, six hundred forty-one".