6991497987 has 8 divisors (see below), whose sum is σ = 9323425104. Its totient is φ = 4660284768.

The previous prime is 6991497967. The next prime is 6991498051. The reversal of 6991497987 is 7897941996.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 6991497987 - 2¹⁸ = 6991235843 is a prime.

It is not an unprimeable number, because it can be changed into a prime (6991497937) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 155188 + ... + 195105.

It is an arithmetic number, because the mean of its divisors is an integer number (1165428138).

Almost surely, 2^6991497987 is an apocalyptic number.

6991497987 is a deficient number, since it is larger than the sum of its proper divisors (2331927117).

6991497987 is a wasteful number, since it uses less digits than its factorization.

6991497987 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 356949.

The product of its digits is 61725888, while the sum is 69.

The square root of 6991497987 is about 83615.1779702704. The cubic root of 6991497987 is about 1912.1564039751.

The spelling of 6991497987 in words is "six billion, nine hundred ninety-one million, four hundred ninety-seven thousand, nine hundred eighty-seven".