645831 has 12 divisors (see below), whose sum is σ = 946608. Its totient is φ = 424224.

The previous prime is 645803. The next prime is 645833. The reversal of 645831 is 138546.

It is not a de Polignac number, because 645831 - 2⁷ = 645703 is a prime.

It is a super-2 number, since 2×645831² = 834195361122, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 645795 and 645804.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645833) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 166 + ... + 1148.

It is an arithmetic number, because the mean of its divisors is an integer number (78884).

2⁶⁴⁵⁸³¹ is an apocalyptic number.

645831 is a deficient number, since it is larger than the sum of its proper divisors (300777).

645831 is a wasteful number, since it uses less digits than its factorization.

645831 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1062 (or 1059 counting only the distinct ones).

The product of its digits is 2880, while the sum is 27.

The square root of 645831 is about 803.6361116824. The cubic root of 645831 is about 86.4383156960.

The spelling of 645831 in words is "six hundred forty-five thousand, eight hundred thirty-one".