66565901 has 2 divisors, whose sum is σ = 66565902. Its totient is φ = 66565900.

The previous prime is 66565867. The next prime is 66565909. The reversal of 66565901 is 10956566.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 63840100 + 2725801 = 7990^2 + 1651^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66565901 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66565909) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33282950 + 33282951.

It is an arithmetic number, because the mean of its divisors is an integer number (33282951).

Almost surely, 2^66565901 is an apocalyptic number.

It is an amenable number.

66565901 is a deficient number, since it is larger than the sum of its proper divisors (1).

66565901 is an equidigital number, since it uses as much as digits as its factorization.

66565901 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 48600, while the sum is 38.

The square root of 66565901 is about 8158.7928641436. The cubic root of 66565901 is about 405.2757376438.

It can be divided in two parts, 665 and 65901, that added together give a palindrome (66566).

The spelling of 66565901 in words is "sixty-six million, five hundred sixty-five thousand, nine hundred one".