1991516476608 has 672 divisors, whose sum is σ = 6450470208000. Its totient is φ = 607297388544.

The previous prime is 1991516476589. The next prime is 1991516476619. The reversal of 1991516476608 is 8066746151991.

1991516476608 is a `hidden beast` number, since 1 + 9 + 9 + 1 + 5 + 16 + 4 + 7 + 6 + 608 = 666.

It is a super-2 number, since 2×1991516476608² (a number of 25 digits) contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 1172168943 + ... + 1172170641.

It is an arithmetic number, because the mean of its divisors is an integer number (9598914000).

Almost surely, 2^{1991516476608} is an apocalyptic number.

1991516476608 is a gapful number since it is divisible by the number (18) 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 1991516476608, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3225235104000).

1991516476608 is an abundant number, since it is smaller than the sum of its proper divisors (4458953731392).

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

1991516476608 is a wasteful number, since it uses less digits than its factorization.

1991516476608 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1891 (or 1869 counting only the distinct ones).

The product of its (nonzero) digits is 19595520, while the sum is 63.

The spelling of 1991516476608 in words is "one trillion, nine hundred ninety-one billion, five hundred sixteen million, four hundred seventy-six thousand, six hundred eight".