645775 has 12 divisors (see below), whose sum is σ = 862792. Its totient is φ = 476640.

The previous prime is 645763. The next prime is 645787. The reversal of 645775 is 577546.

It is an interprime number because it is at equal distance from previous prime (645763) and next prime (645787).

It is not a de Polignac number, because 645775 - 2⁷ = 645647 is a prime.

It is a hoax number, since the sum of its digits (34) coincides with the sum of the digits of its distinct prime factors.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 645775.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 669 + ... + 1318.

2⁶⁴⁵⁷⁷⁵ is an apocalyptic number.

645775 is a gapful number since it is divisible by the number (65) formed by its first and last digit.

645775 is a deficient number, since it is larger than the sum of its proper divisors (217017).

645775 is a wasteful number, since it uses less digits than its factorization.

645775 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2010 (or 2005 counting only the distinct ones).

The product of its digits is 29400, while the sum is 34.

The square root of 645775 is about 803.6012692872. The cubic root of 645775 is about 86.4358172686.

The spelling of 645775 in words is "six hundred forty-five thousand, seven hundred seventy-five".