1991739960 has 192 divisors, whose sum is σ = 7431091200. Its totient is φ = 453212928.

The previous prime is 1991739949. The next prime is 1991739979. The reversal of 1991739960 is 699371991.

1991739960 is a `hidden beast` number, since 199 + 1 + 7 + 399 + 60 = 666.

It is a junction number, because it is equal to n+sod(n) for n = 1991739897 and 1991739906.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 600627 + ... + 603933.

It is an arithmetic number, because the mean of its divisors is an integer number (38703600).

Almost surely, 2^1991739960 is an apocalyptic number.

1991739960 is a gapful number since it is divisible by the number (10) 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 1991739960, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3715545600).

1991739960 is an abundant number, since it is smaller than the sum of its proper divisors (5439351240).

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

1991739960 is a wasteful number, since it uses less digits than its factorization.

1991739960 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3570 (or 3563 counting only the distinct ones).

The product of its (nonzero) digits is 826686, while the sum is 54.

The square root of 1991739960 is about 44628.9139460059. The cubic root of 1991739960 is about 1258.1841568500.

The spelling of 1991739960 in words is "one billion, nine hundred ninety-one million, seven hundred thirty-nine thousand, nine hundred sixty".