669965821 has 12 divisors (see below), whose sum is σ = 808097952. Its totient is φ = 544030344.

The previous prime is 669965797. The next prime is 669965837. The reversal of 669965821 is 128569966.

It is not a de Polignac number, because 669965821 - 2⁷ = 669965693 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (669968821) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 130035 + ... + 135088.

It is an arithmetic number, because the mean of its divisors is an integer number (67341496).

Almost surely, 2^669965821 is an apocalyptic number.

It is an amenable number.

669965821 is a deficient number, since it is larger than the sum of its proper divisors (138132131).

669965821 is a wasteful number, since it uses less digits than its factorization.

669965821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 265168 (or 265149 counting only the distinct ones).

The product of its digits is 1399680, while the sum is 52.

The square root of 669965821 is about 25883.6979776847. The cubic root of 669965821 is about 875.0191325340.

The spelling of 669965821 in words is "six hundred sixty-nine million, nine hundred sixty-five thousand, eight hundred twenty-one".