669491568 has 100 divisors (see below), whose sum is σ = 1951270200. Its totient is φ = 221602176.

The previous prime is 669491539. The next prime is 669491591. The reversal of 669491568 is 865194966.

It is a happy number.

It is a Smith number, since the sum of its digits (54) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 191371 + ... + 194837.

It is an arithmetic number, because the mean of its divisors is an integer number (19512702).

Almost surely, 2^669491568 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 669491568, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (975635100).

669491568 is an abundant number, since it is smaller than the sum of its proper divisors (1281778632).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

669491568 is a wasteful number, since it uses less digits than its factorization.

669491568 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3636 (or 3621 counting only the distinct ones).

The product of its digits is 2799360, while the sum is 54.

The square root of 669491568 is about 25874.5351262588. The cubic root of 669491568 is about 874.8126153295.

The spelling of 669491568 in words is "six hundred sixty-nine million, four hundred ninety-one thousand, five hundred sixty-eight".