6991712640 has 768 divisors, whose sum is σ = 28175696640. Its totient is φ = 1642291200.

The previous prime is 6991712639. The next prime is 6991712647. The reversal of 6991712640 is 462171996.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6991712647) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 104353887 + ... + 104353953.

It is an arithmetic number, because the mean of its divisors is an integer number (36687105).

Almost surely, 2^6991712640 is an apocalyptic number.

6991712640 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 6991712640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (14087848320).

6991712640 is an abundant number, since it is smaller than the sum of its proper divisors (21183984000).

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

6991712640 is a wasteful number, since it uses less digits than its factorization.

6991712640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 173 (or 149 counting only the distinct ones).

The product of its (nonzero) digits is 163296, while the sum is 45.

The square root of 6991712640 is about 83616.4615371878. The cubic root of 6991712640 is about 1912.1759727861.

The spelling of 6991712640 in words is "six billion, nine hundred ninety-one million, seven hundred twelve thousand, six hundred forty".