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, and also a brilliant number, because the two primes have the same length.
It is a cyclic number.
6991669 is a strobogrammatic number because it is the same when read upside-down.
It is a Duffinian number.
It is a congruent number.
Almost surely, 26991669 is an apocalyptic number.
It is an amenable number.
6991669 is a wasteful number, since it uses less digits than its factorization.
6991669 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 5290.
The square root of 6991669 is about 2644.1764313298. The cubic root of 6991669 is about 191.2171994384.
The spelling of 6991669 in words is "six million, nine hundred ninety-one thousand, six hundred sixty-nine".