1991385174636 has 480 divisors, whose sum is σ = 6254640032256. Its totient is φ = 549075542400.

The previous prime is 1991385174523. The next prime is 1991385174637. The reversal of 1991385174636 is 6364715831991.

It is a happy number.

1991385174636 is a `hidden beast` number, since 1 + 9 + 91 + 3 + 85 + 1 + 7 + 463 + 6 = 666.

It is a super-2 number, since 2×1991385174636² (a number of 25 digits) contains 22 as substring.

Its product of digits (29393280) is a multiple of the sum of its prime divisors (5103).

It is not an unprimeable number, because it can be changed into a prime (1991385174637) by changing a digit.

It is a polite number, since it can be written in 159 ways as a sum of consecutive naturals, for example, 398035711 + ... + 398040713.

Almost surely, 2^{1991385174636} is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1991385174636, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3127320016128).

1991385174636 is an abundant number, since it is smaller than the sum of its proper divisors (4263254857620).

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

1991385174636 is a wasteful number, since it uses less digits than its factorization.

1991385174636 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5136 (or 5103 counting only the distinct ones).

The product of its digits is 29393280, while the sum is 63.

The spelling of 1991385174636 in words is "one trillion, nine hundred ninety-one billion, three hundred eighty-five million, one hundred seventy-four thousand, six hundred thirty-six".