66819 has 4 divisors (see below), whose sum is σ = 89096. Its totient is φ = 44544.

The previous prime is 66809. The next prime is 66821. The reversal of 66819 is 91866.

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

It is not a de Polignac number, because 66819 - 2¹² = 62723 is a prime.

It is a super-2 number, since 2×66819² = 8929557522, which contains 22 as substring.

It is a D-number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66809) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 11134 + ... + 11139.

It is an arithmetic number, because the mean of its divisors is an integer number (22274).

2⁶⁶⁸¹⁹ is an apocalyptic number.

66819 is a deficient number, since it is larger than the sum of its proper divisors (22277).

66819 is a wasteful number, since it uses less digits than its factorization.

66819 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22276.

The product of its digits is 2592, while the sum is 30.

The square root of 66819 is about 258.4937136566. The cubic root of 66819 is about 40.5788738804.

The spelling of 66819 in words is "sixty-six thousand, eight hundred nineteen".