66540857 has 2 divisors, whose sum is σ = 66540858. Its totient is φ = 66540856.

The previous prime is 66540847. The next prime is 66540871. The reversal of 66540857 is 75804566.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 63664441 + 2876416 = 7979^2 + 1696^2 .

It is a cyclic number.

It is not a de Polignac number, because 66540857 - 2¹⁴ = 66524473 is a prime.

It is not a weakly prime, because it can be changed into another prime (66540847) 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, 33270428 + 33270429.

It is an arithmetic number, because the mean of its divisors is an integer number (33270429).

Almost surely, 2^66540857 is an apocalyptic number.

It is an amenable number.

66540857 is a deficient number, since it is larger than the sum of its proper divisors (1).

66540857 is an equidigital number, since it uses as much as digits as its factorization.

66540857 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 201600, while the sum is 41.

The square root of 66540857 is about 8157.2579338893. The cubic root of 66540857 is about 405.2249058187.

The spelling of 66540857 in words is "sixty-six million, five hundred forty thousand, eight hundred fifty-seven".