669640 has 16 divisors (see below), whose sum is σ = 1506780. Its totient is φ = 267840.

The previous prime is 669637. The next prime is 669649. The reversal of 669640 is 46966.

669640 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 630436 + 39204 = 794^2 + 198^2 .

It is not an unprimeable number, because it can be changed into a prime (669649) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8331 + ... + 8410.

2⁶⁶⁹⁶⁴⁰ is an apocalyptic number.

It is an amenable number.

669640 is an abundant number, since it is smaller than the sum of its proper divisors (837140).

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

669640 is a wasteful number, since it uses less digits than its factorization.

669640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16752 (or 16748 counting only the distinct ones).

The product of its (nonzero) digits is 7776, while the sum is 31.

The square root of 669640 is about 818.3153426400. The cubic root of 669640 is about 87.4877261696.

The spelling of 669640 in words is "six hundred sixty-nine thousand, six hundred forty".