6405881 has 4 divisors (see below), whose sum is σ = 6562164. Its totient is φ = 6249600.

The previous prime is 6405877. The next prime is 6405899. The reversal of 6405881 is 1885046.

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

It can be written as a sum of positive squares in 2 ways, for example, as 80656 + 6325225 = 284^2 + 2515^2 .

It is a cyclic number.

It is not a de Polignac number, because 6405881 - 2² = 6405877 is a prime.

It is a super-2 number, since 2×6405881² = 82070622772322, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (6405811) 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, 78080 + ... + 78161.

It is an arithmetic number, because the mean of its divisors is an integer number (1640541).

Almost surely, 2^6405881 is an apocalyptic number.

It is an amenable number.

6405881 is a deficient number, since it is larger than the sum of its proper divisors (156283).

6405881 is a wasteful number, since it uses less digits than its factorization.

6405881 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 156282.

The product of its (nonzero) digits is 7680, while the sum is 32.

The square root of 6405881 is about 2530.9841959206. The cubic root of 6405881 is about 185.7204050675.

The spelling of 6405881 in words is "six million, four hundred five thousand, eight hundred eighty-one".