6649987 has 4 divisors (see below), whose sum is σ = 6657120. Its totient is φ = 6642856.

The previous prime is 6649919. The next prime is 6649999. The reversal of 6649987 is 7899466.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 7899466 = 2 ⋅3949733.

It is a cyclic number.

It is not a de Polignac number, because 6649987 - 2⁷ = 6649859 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 6649987.

It is not an unprimeable number, because it can be changed into a prime (6649387) 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, 1912 + ... + 4117.

It is an arithmetic number, because the mean of its divisors is an integer number (1664280).

Almost surely, 2^6649987 is an apocalyptic number.

6649987 is a deficient number, since it is larger than the sum of its proper divisors (7133).

6649987 is a wasteful number, since it uses less digits than its factorization.

6649987 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7132.

The product of its digits is 653184, while the sum is 49.

The square root of 6649987 is about 2578.7568710524. The cubic root of 6649987 is about 188.0501130177.

The spelling of 6649987 in words is "six million, six hundred forty-nine thousand, nine hundred eighty-seven".