Subtracting from 640862 its reverse (268046), we obtain a triangular number (372816 = T863).
It is a semiprime because it is the product of two primes.
It is a congruent number.
It is an unprimeable number.
2640862 is an apocalyptic number.
640862 is a wasteful number, since it uses less digits than its factorization.
640862 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 320433.
The square root of 640862 is about 800.5385687148. The cubic root of 640862 is about 86.2160603003.
The spelling of 640862 in words is "six hundred forty thousand, eight hundred sixty-two".