66138251 has 2 divisors, whose sum is σ = 66138252. Its totient is φ = 66138250.

The previous prime is 66138239. The next prime is 66138263. The reversal of 66138251 is 15283166.

It is a happy number.

66138251 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a balanced prime because it is at equal distance from previous prime (66138239) and next prime (66138263).

It is a cyclic number.

It is not a de Polignac number, because 66138251 - 2⁶ = 66138187 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (66138851) 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, 33069125 + 33069126.

It is an arithmetic number, because the mean of its divisors is an integer number (33069126).

Almost surely, 2^66138251 is an apocalyptic number.

66138251 is a deficient number, since it is larger than the sum of its proper divisors (1).

66138251 is an equidigital number, since it uses as much as digits as its factorization.

66138251 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 8640, while the sum is 32.

The square root of 66138251 is about 8132.5427143053. The cubic root of 66138251 is about 404.4059797483.

The spelling of 66138251 in words is "sixty-six million, one hundred thirty-eight thousand, two hundred fifty-one".