2191791420 has 576 divisors, whose sum is σ = 8736215040. Its totient is φ = 446404608.

The previous prime is 2191791409. The next prime is 2191791421. The reversal of 2191791420 is 241971912.

2191791420 is a `hidden beast` number, since 219 + 17 + 9 + 1 + 420 = 666.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2191791421) by changing a digit.

It is a polite number, since it can be written in 191 ways as a sum of consecutive naturals, for example, 30024504 + ... + 30024576.

It is an arithmetic number, because the mean of its divisors is an integer number (15167040).

Almost surely, 2^2191791420 is an apocalyptic number.

2191791420 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 2191791420, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (4368107520).

2191791420 is an abundant number, since it is smaller than the sum of its proper divisors (6544423620).

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

2191791420 is a wasteful number, since it uses less digits than its factorization.

2191791420 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 171 (or 150 counting only the distinct ones).

The product of its (nonzero) digits is 9072, while the sum is 36.

The square root of 2191791420 is about 46816.5720658828. The cubic root of 2191791420 is about 1298.9718537389.

The spelling of 2191791420 in words is "two billion, one hundred ninety-one million, seven hundred ninety-one thousand, four hundred twenty".