6939991 has 4 divisors (see below), whose sum is σ = 6949984. Its totient is φ = 6930000.

The previous prime is 6939967. The next prime is 6940007. The reversal of 6939991 is 1999396.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 6939991 - 2¹¹ = 6937943 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6939901) 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, 3870 + ... + 5371.

It is an arithmetic number, because the mean of its divisors is an integer number (1737496).

Almost surely, 2^6939991 is an apocalyptic number.

6939991 is a deficient number, since it is larger than the sum of its proper divisors (9993).

6939991 is an equidigital number, since it uses as much as digits as its factorization.

6939991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9992.

The product of its digits is 118098, while the sum is 46.

The square root of 6939991 is about 2634.3862662867. The cubic root of 6939991 is about 190.7449150008.

The spelling of 6939991 in words is "six million, nine hundred thirty-nine thousand, nine hundred ninety-one".