645777 has 18 divisors (see below), whose sum is σ = 1027026. Its totient is φ = 390720.

The previous prime is 645763. The next prime is 645787. The reversal of 645777 is 777546.

645777 is a `hidden beast` number, since 645 + 7 + 7 + 7 = 666.

645777 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in only one way, i.e., 576081 + 69696 = 759^2 + 264^2 .

It is not a de Polignac number, because 645777 - 2⁶ = 645713 is a prime.

It is not an unprimeable number, because it can be changed into a prime (645727) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 793 + ... + 1385.

It is an arithmetic number, because the mean of its divisors is an integer number (57057).

2⁶⁴⁵⁷⁷⁷ is an apocalyptic number.

It is an amenable number.

645777 is a deficient number, since it is larger than the sum of its proper divisors (381249).

645777 is a wasteful number, since it uses less digits than its factorization.

645777 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 621 (or 607 counting only the distinct ones).

The product of its digits is 41160, while the sum is 36.

The square root of 645777 is about 803.6025136845. The cubic root of 645777 is about 86.4359065006.

Subtracting 645777 from its reverse (777546), we obtain a square (131769 = 363²).

The spelling of 645777 in words is "six hundred forty-five thousand, seven hundred seventy-seven".