66555553 has 2 divisors, whose sum is σ = 66555554. Its totient is φ = 66555552.

The previous prime is 66555539. The next prime is 66555581. The reversal of 66555553 is 35555566.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 66389904 + 165649 = 8148^2 + 407^2 .

It is a cyclic number.

It is not a de Polignac number, because 66555553 - 2⁵ = 66555521 is a prime.

It is a nialpdrome in base 10.

It is not a weakly prime, because it can be changed into another prime (66555653) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33277776 + 33277777.

It is an arithmetic number, because the mean of its divisors is an integer number (33277777).

Almost surely, 2^66555553 is an apocalyptic number.

It is an amenable number.

66555553 is a deficient number, since it is larger than the sum of its proper divisors (1).

66555553 is an equidigital number, since it uses as much as digits as its factorization.

66555553 is an evil number, because the sum of its binary digits is even.

The product of its digits is 337500, while the sum is 40.

The square root of 66555553 is about 8158.1586770545. The cubic root of 66555553 is about 405.2547358466.

The spelling of 66555553 in words is "sixty-six million, five hundred fifty-five thousand, five hundred fifty-three".