400 (number) third perfect number, a number whose divisors add up to the actual number (1+2+4+8+16+31+62+124+248=496). 497 = 7 × 71, sum of five consecutive primes (89 + 97 + 101 + 103 + 107) 498 = 2 × 3 × 83, sphenic number, untouchable number, admirable number, abundant number A prime number, Chen prime 400 (number) 400 (four hundred) is the natural number following 399 and preceding 401. 400 is the square of 20. 400 is the sum of the powers of 7 from 0 to 3, thus making it a repdigit in base 7 (1111). A circle is divided into
Multiplicative digital root of 9876 is 0 and its multiplicative persistence (the number of steps required to reach a single digit) is 2. Multiplicative digital root The multiplicative digital root of a positive integer "n" is found by multiplying the digits of "n" together, then repeating this operation until only a single digit remains. This single-digit number is called the multiplicative digital root of "n". Multiplicative digital roots depend upon the base in which "n" is written. If the term is used without qualification, it is assumed that "n" is written in base 10. Multiplicative digital roots are the multiplicative equivalent of digital