669940 has 48 divisors (see below), whose sum is σ = 1552320. Its totient is φ = 241920.

The previous prime is 669937. The next prime is 669943. The reversal of 669940 is 49966.

669940 = T₂₅₆ + T₂₅₇ + ... + T₂₇₄.

669940 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (669937) and next prime (669943).

It is a junction number, because it is equal to n+sod(n) for n = 669896 and 669905.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (669943) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 15559 + ... + 15601.

It is an arithmetic number, because the mean of its divisors is an integer number (32340).

2⁶⁶⁹⁹⁴⁰ 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 669940, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (776160).

669940 is an abundant number, since it is smaller than the sum of its proper divisors (882380).

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

669940 is a wasteful number, since it uses less digits than its factorization.

669940 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 112 (or 110 counting only the distinct ones).

The product of its (nonzero) digits is 11664, while the sum is 34.

The square root of 669940 is about 818.4986255334. The cubic root of 669940 is about 87.5007891085.

The spelling of 669940 in words is "six hundred sixty-nine thousand, nine hundred forty".