66520061 has 2 divisors, whose sum is σ = 66520062. Its totient is φ = 66520060.

The previous prime is 66520039. The next prime is 66520063. The reversal of 66520061 is 16002566.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 54479161 + 12040900 = 7381^2 + 3470^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66520061 is a prime.

Together with 66520063, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 66520061.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66520063) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33260030 + 33260031.

It is an arithmetic number, because the mean of its divisors is an integer number (33260031).

Almost surely, 2^66520061 is an apocalyptic number.

It is an amenable number.

66520061 is a deficient number, since it is larger than the sum of its proper divisors (1).

66520061 is an equidigital number, since it uses as much as digits as its factorization.

66520061 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2160, while the sum is 26.

The square root of 66520061 is about 8155.9831412283. The cubic root of 66520061 is about 405.1826864687.

The spelling of 66520061 in words is "sixty-six million, five hundred twenty thousand, sixty-one".