669749 has 4 divisors (see below), whose sum is σ = 709164. Its totient is φ = 630336.

The previous prime is 669733. The next prime is 669763. The reversal of 669749 is 947966.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 504100 + 165649 = 710^2 + 407^2 .

It is a cyclic number.

It is not a de Polignac number, because 669749 - 2⁴ = 669733 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 (669049) 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, 19682 + ... + 19715.

It is an arithmetic number, because the mean of its divisors is an integer number (177291).

2⁶⁶⁹⁷⁴⁹ is an apocalyptic number.

It is an amenable number.

669749 is a deficient number, since it is larger than the sum of its proper divisors (39415).

669749 is a wasteful number, since it uses less digits than its factorization.

669749 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 39414.

The product of its digits is 81648, while the sum is 41.

The square root of 669749 is about 818.3819401722. The cubic root of 669749 is about 87.4924728219.

The spelling of 669749 in words is "six hundred sixty-nine thousand, seven hundred forty-nine".