6991989 has 4 divisors (see below), whose sum is σ = 9322656. Its totient is φ = 4661324.

The previous prime is 6991979. The next prime is 6991991. The reversal of 6991989 is 9891996.

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.

It is a cyclic number.

It is not a de Polignac number, because 6991989 - 2⁴ = 6991973 is a prime.

It is a super-2 number, since 2×6991989² = 97775820352242, which contains 22 as substring.

It is a D-number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6991939) 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, 1165329 + ... + 1165334.

It is an arithmetic number, because the mean of its divisors is an integer number (2330664).

Almost surely, 2^6991989 is an apocalyptic number.

It is an amenable number.

6991989 is a deficient number, since it is larger than the sum of its proper divisors (2330667).

6991989 is a wasteful number, since it uses less digits than its factorization.

6991989 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2330666.

The product of its digits is 314928, while the sum is 51.

The square root of 6991989 is about 2644.2369409718. The cubic root of 6991989 is about 191.2201166517.

The spelling of 6991989 in words is "six million, nine hundred ninety-one thousand, nine hundred eighty-nine".