645769 has 4 divisors (see below), whose sum is σ = 647680. Its totient is φ = 643860.

The previous prime is 645763. The next prime is 645787. The reversal of 645769 is 967546.

645769 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 967546 = 2 ⋅483773.

It is a cyclic number.

It is not a de Polignac number, because 645769 - 2⁵ = 645737 is a prime.

It is a super-2 number, since 2×645769² = 834035202722, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (645763) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 297 + ... + 1174.

It is an arithmetic number, because the mean of its divisors is an integer number (161920).

2⁶⁴⁵⁷⁶⁹ is an apocalyptic number.

It is an amenable number.

645769 is a deficient number, since it is larger than the sum of its proper divisors (1911).

645769 is a wasteful number, since it uses less digits than its factorization.

645769 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1910.

The product of its digits is 45360, while the sum is 37.

The square root of 645769 is about 803.5975360838. The cubic root of 645769 is about 86.4355495714.

The spelling of 645769 in words is "six hundred forty-five thousand, seven hundred sixty-nine".