645776 has 10 divisors (see below), whose sum is σ = 1251222. Its totient is φ = 322880.

The previous prime is 645763. The next prime is 645787. The reversal of 645776 is 677546.

It can be written as a sum of positive squares in only one way, i.e., 640000 + 5776 = 800^2 + 76^2 .

It is an unprimeable number.

645776 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20165 + ... + 20196.

2⁶⁴⁵⁷⁷⁶ is an apocalyptic number.

It is an amenable number.

645776 is a deficient number, since it is larger than the sum of its proper divisors (605446).

645776 is a wasteful number, since it uses less digits than its factorization.

645776 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40369 (or 40363 counting only the distinct ones).

The product of its digits is 35280, while the sum is 35.

The square root of 645776 is about 803.6018914861. The cubic root of 645776 is about 86.4358618846.

It can be divided in two parts, 64 and 5776, that multiplied together give a square (369664 = 608²).

The spelling of 645776 in words is "six hundred forty-five thousand, seven hundred seventy-six".