646531 has 4 divisors (see below), whose sum is σ = 652912. Its totient is φ = 640152.

The previous prime is 646523. The next prime is 646537. The reversal of 646531 is 135646.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 646531 - 2³ = 646523 is a prime.

It is a super-2 number, since 2×646531² = 836004667922, which contains 22 as substring.

It is a Duffinian number.

It is a nialpdrome in base 15.

It is a junction number, because it is equal to n+sod(n) for n = 646496 and 646505.

It is not an unprimeable number, because it can be changed into a prime (646537) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3036 + ... + 3241.

It is an arithmetic number, because the mean of its divisors is an integer number (163228).

2⁶⁴⁶⁵³¹ is an apocalyptic number.

646531 is a deficient number, since it is larger than the sum of its proper divisors (6381).

646531 is a wasteful number, since it uses less digits than its factorization.

646531 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6380.

The product of its digits is 2160, while the sum is 25.

The square root of 646531 is about 804.0715142324. The cubic root of 646531 is about 86.4695338596.

The spelling of 646531 in words is "six hundred forty-six thousand, five hundred thirty-one".