6645880581 has 4 divisors (see below), whose sum is σ = 8861174112. Its totient is φ = 4430587052.

The previous prime is 6645880573. The next prime is 6645880583. The reversal of 6645880581 is 1850885466.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 6645880581 - 2³ = 6645880573 is a prime.

It is a super-2 number, since 2×6645880581² = 88335457393825795122, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6645880583) 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, 1107646761 + ... + 1107646766.

It is an arithmetic number, because the mean of its divisors is an integer number (2215293528).

Almost surely, 2^6645880581 is an apocalyptic number.

It is an amenable number.

6645880581 is a deficient number, since it is larger than the sum of its proper divisors (2215293531).

6645880581 is a wasteful number, since it uses less digits than its factorization.

6645880581 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2215293530.

The product of its (nonzero) digits is 1843200, while the sum is 51.

The square root of 6645880581 is about 81522.2704602859. The cubic root of 6645880581 is about 1880.1139757556.

The spelling of 6645880581 in words is "six billion, six hundred forty-five million, eight hundred eighty thousand, five hundred eighty-one".