669478891 has 12 divisors (see below), whose sum is σ = 695887192. Its totient is φ = 644039424.

The previous prime is 669478879. The next prime is 669478897. The reversal of 669478891 is 198874966.

It is not a de Polignac number, because 669478891 - 2²¹ = 667381739 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (669478897) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 256891 + ... + 259483.

Almost surely, 2^669478891 is an apocalyptic number.

669478891 is a deficient number, since it is larger than the sum of its proper divisors (26408301).

669478891 is a wasteful number, since it uses less digits than its factorization.

669478891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2958 (or 2929 counting only the distinct ones).

The product of its digits is 5225472, while the sum is 58.

The square root of 669478891 is about 25874.2901545144. The cubic root of 669478891 is about 874.8070936918.

The spelling of 669478891 in words is "six hundred sixty-nine million, four hundred seventy-eight thousand, eight hundred ninety-one".