2091781440 has 672 divisors, whose sum is σ = 8926494720. Its totient is φ = 438939648.

The previous prime is 2091781427. The next prime is 2091781441. The reversal of 2091781440 is 441871902.

2091781440 is a `hidden beast` number, since 209 + 1 + 7 + 8 + 1 + 440 = 666.

It is a tau number, because it is divible by the number of its divisors (672).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 2091781395 and 2091781404.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2091781441) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 16470657 + ... + 16470783.

Almost surely, 2^2091781440 is an apocalyptic number.

2091781440 is a gapful number since it is divisible by the number (20) 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 2091781440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (4463247360).

2091781440 is an abundant number, since it is smaller than the sum of its proper divisors (6834713280).

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

2091781440 is a wasteful number, since it uses less digits than its factorization.

2091781440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 219 (or 206 counting only the distinct ones).

The product of its (nonzero) digits is 16128, while the sum is 36.

The square root of 2091781440 is about 45735.9972013293. The cubic root of 2091781440 is about 1278.9064227313.

The spelling of 2091781440 in words is "two billion, ninety-one million, seven hundred eighty-one thousand, four hundred forty".