66861541 has 2 divisors, whose sum is σ = 66861542. Its totient is φ = 66861540.

The previous prime is 66861539. The next prime is 66861577. The reversal of 66861541 is 14516866.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 56325025 + 10536516 = 7505^2 + 3246^2 .

It is a cyclic number.

It is not a de Polignac number, because 66861541 - 2¹ = 66861539 is a prime.

Together with 66861539, it forms a pair of twin primes.

It is a self number, because there is not a number n which added to its sum of digits gives 66861541.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66861241) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33430770 + 33430771.

It is an arithmetic number, because the mean of its divisors is an integer number (33430771).

Almost surely, 2^66861541 is an apocalyptic number.

It is an amenable number.

66861541 is a deficient number, since it is larger than the sum of its proper divisors (1).

66861541 is an equidigital number, since it uses as much as digits as its factorization.

66861541 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 34560, while the sum is 37.

The square root of 66861541 is about 8176.8906682186. The cubic root of 66861541 is about 405.8748370523.

The spelling of 66861541 in words is "sixty-six million, eight hundred sixty-one thousand, five hundred forty-one".