6646989887 has 4 divisors (see below), whose sum is σ = 6996831480. Its totient is φ = 6297148296.

The previous prime is 6646989883. The next prime is 6646989889. The reversal of 6646989887 is 7889896466.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 7889896466 = 2 ⋅3944948233.

It is a cyclic number.

It is not a de Polignac number, because 6646989887 - 2² = 6646989883 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 6646989887.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6646989883) 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, 174920768 + ... + 174920805.

It is an arithmetic number, because the mean of its divisors is an integer number (1749207870).

Almost surely, 2^6646989887 is an apocalyptic number.

6646989887 is a deficient number, since it is larger than the sum of its proper divisors (349841593).

6646989887 is a wasteful number, since it uses less digits than its factorization.

6646989887 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 349841592.

The product of its digits is 250822656, while the sum is 71.

The square root of 6646989887 is about 81529.0738755200. The cubic root of 6646989887 is about 1880.2185771779.

The spelling of 6646989887 in words is "six billion, six hundred forty-six million, nine hundred eighty-nine thousand, eight hundred eighty-seven".