66665251 has 2 divisors, whose sum is σ = 66665252. Its totient is φ = 66665250.

The previous prime is 66665233. The next prime is 66665273. The reversal of 66665251 is 15256666.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 66665251 - 2²³ = 58276643 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 66665251.

It is not a weakly prime, because it can be changed into another prime (66665051) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33332625 + 33332626.

It is an arithmetic number, because the mean of its divisors is an integer number (33332626).

Almost surely, 2^66665251 is an apocalyptic number.

66665251 is a deficient number, since it is larger than the sum of its proper divisors (1).

66665251 is an equidigital number, since it uses as much as digits as its factorization.

66665251 is an evil number, because the sum of its binary digits is even.

The product of its digits is 64800, while the sum is 37.

The square root of 66665251 is about 8164.8791172926. The cubic root of 66665251 is about 405.4772628944.

The spelling of 66665251 in words is "sixty-six million, six hundred sixty-five thousand, two hundred fifty-one".