645786 has 16 divisors (see below), whose sum is σ = 1435200. Its totient is φ = 215244.

The previous prime is 645763. The next prime is 645787. The reversal of 645786 is 687546.

It is a happy number.

645786 is a `hidden beast` number, since 645 + 7 + 8 + 6 = 666.

It is a Smith number, since the sum of its digits (36) coincides with the sum of the digits of its prime factors.

It is an Ulam number.

It is a self number, because there is not a number n which added to its sum of digits gives 645786.

It is not an unprimeable number, because it can be changed into a prime (645787) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5926 + ... + 6033.

It is an arithmetic number, because the mean of its divisors is an integer number (89700).

2⁶⁴⁵⁷⁸⁶ is an apocalyptic number.

645786 is an abundant number, since it is smaller than the sum of its proper divisors (789414).

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

645786 is a wasteful number, since it uses less digits than its factorization.

645786 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11970 (or 11964 counting only the distinct ones).

The product of its digits is 40320, while the sum is 36.

The square root of 645786 is about 803.6081134483. The cubic root of 645786 is about 86.4363080425.

It can be divided in two parts, 645 and 786, that added together give a triangular number (1431 = T₅₃).

The spelling of 645786 in words is "six hundred forty-five thousand, seven hundred eighty-six".