66690257 has 2 divisors, whose sum is σ = 66690258. Its totient is φ = 66690256.

The previous prime is 66690241. The next prime is 66690287. The reversal of 66690257 is 75209666.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 52432081 + 14258176 = 7241^2 + 3776^2 .

It is a cyclic number.

It is not a de Polignac number, because 66690257 - 2⁴ = 66690241 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (66690287) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33345128 + 33345129.

It is an arithmetic number, because the mean of its divisors is an integer number (33345129).

Almost surely, 2^66690257 is an apocalyptic number.

It is an amenable number.

66690257 is a deficient number, since it is larger than the sum of its proper divisors (1).

66690257 is an equidigital number, since it uses as much as digits as its factorization.

66690257 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 136080, while the sum is 41.

The square root of 66690257 is about 8166.4102884927. The cubic root of 66690257 is about 405.5279544555.

The spelling of 66690257 in words is "sixty-six million, six hundred ninety thousand, two hundred fifty-seven".