646401 has 8 divisors (see below), whose sum is σ = 985024. Its totient is φ = 369360.

The previous prime is 646397. The next prime is 646403. The reversal of 646401 is 104646.

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

It is not a de Polignac number, because 646401 - 2² = 646397 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (21), and also a Moran number because the ratio is a prime number: 30781 = 646401 / (6 + 4 + 6 + 4 + 0 + 1).

It is a Duffinian number.

646401 is a lucky number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 646401.

It is not an unprimeable number, because it can be changed into a prime (646403) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 15370 + ... + 15411.

It is an arithmetic number, because the mean of its divisors is an integer number (123128).

2⁶⁴⁶⁴⁰¹ is an apocalyptic number.

It is an amenable number.

646401 is a deficient number, since it is larger than the sum of its proper divisors (338623).

646401 is a wasteful number, since it uses less digits than its factorization.

646401 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 30791.

The product of its (nonzero) digits is 576, while the sum is 21.

The square root of 646401 is about 803.9906715877. The cubic root of 646401 is about 86.4637379051.

The spelling of 646401 in words is "six hundred forty-six thousand, four hundred one".