669398521 has 8 divisors (see below), whose sum is σ = 739497600. Its totient is φ = 600840240.

The previous prime is 669398497. The next prime is 669398573. The reversal of 669398521 is 125893966.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a de Polignac number, because none of the positive numbers 2^k-669398521 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (669398621) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 384286 + ... + 386023.

It is an arithmetic number, because the mean of its divisors is an integer number (92437200).

Almost surely, 2^669398521 is an apocalyptic number.

It is an amenable number.

669398521 is a deficient number, since it is larger than the sum of its proper divisors (70099079).

669398521 is a wasteful number, since it uses less digits than its factorization.

669398521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 770399.

The product of its digits is 699840, while the sum is 49.

The square root of 669398521 is about 25872.7370218151. The cubic root of 669398521 is about 874.7720858369.

The spelling of 669398521 in words is "six hundred sixty-nine million, three hundred ninety-eight thousand, five hundred twenty-one".