6643915881 has 4 divisors (see below), whose sum is σ = 8858554512. Its totient is φ = 4429277252.

The previous prime is 6643915847. The next prime is 6643915891. The reversal of 6643915881 is 1885193466.

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 6643915881 - 2¹⁴ = 6643899497 is a prime.

It is a super-2 number, since 2×6643915881² = 88283236467608012322, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (6643915891) 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, 1107319311 + ... + 1107319316.

It is an arithmetic number, because the mean of its divisors is an integer number (2214638628).

Almost surely, 2^6643915881 is an apocalyptic number.

It is an amenable number.

6643915881 is a deficient number, since it is larger than the sum of its proper divisors (2214638631).

6643915881 is a wasteful number, since it uses less digits than its factorization.

6643915881 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2214638630.

The product of its digits is 1244160, while the sum is 51.

The square root of 6643915881 is about 81510.2194881108. The cubic root of 6643915881 is about 1879.9286868415.

The spelling of 6643915881 in words is "six billion, six hundred forty-three million, nine hundred fifteen thousand, eight hundred eighty-one".