6405491 has 4 divisors (see below), whose sum is σ = 6626400. Its totient is φ = 6184584.

The previous prime is 6405473. The next prime is 6405493. The reversal of 6405491 is 1945046.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-6405491 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (29), and also a Moran number because the ratio is a prime number: 220879 = 6405491 / (6 + 4 + 0 + 5 + 4 + 9 + 1).

It is a d-powerful number, because it can be written as 6⁸ + 4 + 0 + 5³ + 4¹¹ + 9⁶ + 1 .

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (6405493) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 110411 + ... + 110468.

It is an arithmetic number, because the mean of its divisors is an integer number (1656600).

Almost surely, 2^6405491 is an apocalyptic number.

6405491 is a deficient number, since it is larger than the sum of its proper divisors (220909).

6405491 is a wasteful number, since it uses less digits than its factorization.

6405491 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 220908.

The product of its (nonzero) digits is 4320, while the sum is 29.

The square root of 6405491 is about 2530.9071496205. The cubic root of 6405491 is about 185.7166360086.

The spelling of 6405491 in words is "six million, four hundred five thousand, four hundred ninety-one".