66550819 has 4 divisors (see below), whose sum is σ = 67209840. Its totient is φ = 65891800.

The previous prime is 66550807. The next prime is 66550829. The reversal of 66550819 is 91805566.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 66550819 - 2¹⁹ = 66026531 is a prime.

It is a super-2 number, since 2×66550819² = 8858023019141522, which contains 22 as substring.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66550829) 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 in 3 ways as a sum of consecutive naturals, for example, 329359 + ... + 329560.

It is an arithmetic number, because the mean of its divisors is an integer number (16802460).

Almost surely, 2^66550819 is an apocalyptic number.

66550819 is a deficient number, since it is larger than the sum of its proper divisors (659021).

66550819 is a wasteful number, since it uses less digits than its factorization.

66550819 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 659020.

The product of its (nonzero) digits is 64800, while the sum is 40.

The square root of 66550819 is about 8157.8685328951. The cubic root of 66550819 is about 405.2451272248.

The spelling of 66550819 in words is "sixty-six million, five hundred fifty thousand, eight hundred nineteen".