645687 has 24 divisors (see below), whose sum is σ = 1098656. Its totient is φ = 357696.

The previous prime is 645683. The next prime is 645691. The reversal of 645687 is 786546.

It is a happy number.

645687 is a `hidden beast` number, since 645 + 6 + 8 + 7 = 666.

It is an interprime number because it is at equal distance from previous prime (645683) and next prime (645691).

It is not a de Polignac number, because 645687 - 2² = 645683 is a prime.

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

It is a Duffinian number.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 645687.

It is not an unprimeable number, because it can be changed into a prime (645683) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2193 + ... + 2469.

2⁶⁴⁵⁶⁸⁷ is an apocalyptic number.

645687 is a deficient number, since it is larger than the sum of its proper divisors (452969).

645687 is a wasteful number, since it uses less digits than its factorization.

645687 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 327 (or 324 counting only the distinct ones).

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

The square root of 645687 is about 803.5465138995. The cubic root of 645687 is about 86.4318908766.

The spelling of 645687 in words is "six hundred forty-five thousand, six hundred eighty-seven".