6991866 has 64 divisors (see below), whose sum is σ = 18144000. Its totient is φ = 1954368.

The previous prime is 6991847. The next prime is 6991877. The reversal of 6991866 is 6681996.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 19860 + ... + 20208.

It is an arithmetic number, because the mean of its divisors is an integer number (283500).

Almost surely, 2^6991866 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 6991866, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (9072000).

6991866 is an abundant number, since it is smaller than the sum of its proper divisors (11152134).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

6991866 is a wasteful number, since it uses less digits than its factorization.

6991866 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 420 (or 414 counting only the distinct ones).

The product of its digits is 139968, while the sum is 45.

The square root of 6991866 is about 2644.2136827420. The cubic root of 6991866 is about 191.2189953584.

The spelling of 6991866 in words is "six million, nine hundred ninety-one thousand, eight hundred sixty-six".