646431 has 8 divisors (see below), whose sum is σ = 868224. Its totient is φ = 427800.

The previous prime is 646423. The next prime is 646433. The reversal of 646431 is 134646.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 646431 - 2³ = 646423 is a prime.

It is a super-2 number, since 2×646431² = 835746075522, which contains 22 as substring.

It is a Smith number, since the sum of its digits (24) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (646433) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 261 + ... + 1166.

It is an arithmetic number, because the mean of its divisors is an integer number (108528).

2⁶⁴⁶⁴³¹ is an apocalyptic number.

646431 is the 509-th centered pentagonal number.

646431 is a deficient number, since it is larger than the sum of its proper divisors (221793).

646431 is a wasteful number, since it uses less digits than its factorization.

646431 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1581.

The product of its digits is 1728, while the sum is 24.

The square root of 646431 is about 804.0093283041. The cubic root of 646431 is about 86.4650755020.

The spelling of 646431 in words is "six hundred forty-six thousand, four hundred thirty-one".