6445781558 has 4 divisors (see below), whose sum is σ = 9668672340. Its totient is φ = 3222890778.

The previous prime is 6445781549. The next prime is 6445781621. The reversal of 6445781558 is 8551875446.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 8551875446 = 2 ⋅4275937723.

It is a congruent number.

It is an unprimeable number.

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 as a sum of consecutive naturals, namely, 1611445388 + ... + 1611445391.

It is an arithmetic number, because the mean of its divisors is an integer number (2417168085).

Almost surely, 2^6445781558 is an apocalyptic number.

6445781558 is a deficient number, since it is larger than the sum of its proper divisors (3222890782).

6445781558 is a wasteful number, since it uses less digits than its factorization.

6445781558 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3222890781.

The product of its digits is 5376000, while the sum is 53.

The square root of 6445781558 is about 80285.6248527717. The cubic root of 6445781558 is about 1861.0520850607.

The spelling of 6445781558 in words is "six billion, four hundred forty-five million, seven hundred eighty-one thousand, five hundred fifty-eight".