669780 has 54 divisors (see below), whose sum is σ = 2065518. Its totient is φ = 175680.

The previous prime is 669763. The next prime is 669787. The reversal of 669780 is 87966.

It can be written as a sum of positive squares in 3 ways, for example, as 51984 + 617796 = 228^2 + 786^2 .

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (669787) by changing a digit.

669780 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 10950 + ... + 11010.

2⁶⁶⁹⁷⁸⁰ is an apocalyptic number.

669780 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 669780, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1032759).

669780 is an abundant number, since it is smaller than the sum of its proper divisors (1395738).

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

669780 is a wasteful number, since it uses less digits than its factorization.

669780 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 137 (or 71 counting only the distinct ones).

The product of its (nonzero) digits is 18144, while the sum is 36.

The square root of 669780 is about 818.4008797649. The cubic root of 669780 is about 87.4938226932.

The spelling of 669780 in words is "six hundred sixty-nine thousand, seven hundred eighty".