Number of the day: 87790013

Ky Fan was born on this day 106 years ago.

Properties of the number 87790013:

87790013 is a cyclic number.
87790013 = 19 × 83 × 179 × 311 is the 82693698^th composite number and is squarefree.
87790013 has 4 distinct prime factors, 16 divisors, 39 antidivisors and 81445680 totatives.
87790013 has a semiprime digit sum 35 in base 10.
Reversing the decimal digits of 87790013 results in a semiprime.
87790013 = 43895007² - 43895006² = 2310273² - 2310254² = 528897² - 528814² = 245313² - 245134² = 141297² - 140986² = 28623² - 27046² = 14607² - 11206² = 10383² - 4474² is the difference of 2 nonnegative squares in 8 ways.
87790013 is the difference of 2 positive pentagonal numbers in 8 ways.
87790013 = 109² + 306² + 9364² is the sum of 3 positive squares.
87790013² is the sum of 3 positive squares.
87790013 is a proper divisor of 331¹⁶⁵⁵⁴ - 1.
87790013 = '87' + '790013' is the concatenation of 2 semiprime numbers.