6991616520 has 256 divisors, whose sum is σ = 28201996800. Its totient is φ = 1504051200.

The previous prime is 6991616497. The next prime is 6991616551. The reversal of 6991616520 is 256161996.

It is a happy number.

6991616520 is a `hidden beast` number, since 6 + 9 + 9 + 1 + 616 + 5 + 20 = 666.

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

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 101320 + ... + 155720.

It is an arithmetic number, because the mean of its divisors is an integer number (110164050).

Almost surely, 2^6991616520 is an apocalyptic number.

6991616520 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 6991616520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (14100998400).

6991616520 is an abundant number, since it is smaller than the sum of its proper divisors (21210380280).

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

6991616520 is a wasteful number, since it uses less digits than its factorization.

6991616520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 54445 (or 54435 counting only the distinct ones).

The product of its (nonzero) digits is 174960, while the sum is 45.

The square root of 6991616520 is about 83615.8867680060. The cubic root of 6991616520 is about 1912.1672100692.

It can be divided in two parts, 69916 and 16520, that added together give a square (86436 = 294²).

The spelling of 6991616520 in words is "six billion, nine hundred ninety-one million, six hundred sixteen thousand, five hundred twenty".