1991737921536 has 1664 divisors, whose sum is σ = 7311981196800. Its totient is φ = 535088332800.

The previous prime is 1991737921529. The next prime is 1991737921543. The reversal of 1991737921536 is 6351297371991.

1991737921536 is a `hidden beast` number, since 1 + 9 + 9 + 1 + 7 + 3 + 7 + 92 + 1 + 536 = 666.

It is an interprime number because it is at equal distance from previous prime (1991737921529) and next prime (1991737921543).

It is a super-3 number, since 3×1991737921536³ (a number of 38 digits) contains 333 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 48578973676 + ... + 48578973716.

Almost surely, 2^{1991737921536} is an apocalyptic number.

1991737921536 is a gapful number since it is divisible by the number (16) 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 1991737921536, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3655990598400).

1991737921536 is an abundant number, since it is smaller than the sum of its proper divisors (5320243275264).

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

1991737921536 is an equidigital number, since it uses as much as digits as its factorization.

1991737921536 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 143 (or 103 counting only the distinct ones).

The product of its digits is 19289340, while the sum is 63.

The spelling of 1991737921536 in words is "one trillion, nine hundred ninety-one billion, seven hundred thirty-seven million, nine hundred twenty-one thousand, five hundred thirty-six".