690
690 is an integer that follows 689 and precedes 691. It is even and composite, with prime factorization 2 × 3 × 5 × 23. Consequently, it has 16 positive divisors. The sum of its divisors is 1728, and its Euler totient is 176. As a base-10 number, 690 is a Harshad (Niven) number because its digits sum to 15 and 690 is divisible by 15.
In numeral systems, 690 is written as DCXC in Roman numerals. In hexadecimal it is 2B2, in
690 Wratislavia is a main-belt asteroid designated with the number 690.
As a calendar year, 690 CE falls in the late 7th century of the common era, a