669644819 has 4 divisors (see below), whose sum is σ = 669700944. Its totient is φ = 669588696.

The previous prime is 669644809. The next prime is 669644821. The reversal of 669644819 is 918446966.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 669644819 - 2⁴ = 669644803 is a prime.

It is a super-2 number, since 2×669644819² = 896848367227085522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (669644809) 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, 2252 + ... + 36665.

It is an arithmetic number, because the mean of its divisors is an integer number (167425236).

Almost surely, 2^669644819 is an apocalyptic number.

669644819 is a deficient number, since it is larger than the sum of its proper divisors (56125).

669644819 is a wasteful number, since it uses less digits than its factorization.

669644819 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 56124.

The product of its digits is 2239488, while the sum is 53.

The square root of 669644819 is about 25877.4963819918. The cubic root of 669644819 is about 874.8793603473.

It can be divided in two parts, 6696 and 44819, that added together give a palindrome (51515).

The spelling of 669644819 in words is "six hundred sixty-nine million, six hundred forty-four thousand, eight hundred nineteen".